Term
Start of Chpt. 10
What is the purpose of starting a relay?
a. to start an electric motor
b. to remove the starting winding or component from the circuit
c. to protect the motor from starting overloads
d. to prevent the motor from starting under heavy loads |
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Definition
| b. to remove the starting winding or component from the circuit |
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Term
| Explain the operating principle of a potential relay. |
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Definition
| The back EMF of the motor determinds when the relay is energized, thus opening a set of contacts dropping the starting capacitor or winding from the electrical circuit when the motor reaches 75% of full speed. |
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Term
| Explain the operating principle of a current relay. |
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Definition
| The current of the motor determins when the relay is de-energized, thus opening a set of contacts dropping the starting capacitor or winding from the electrical circuit when the motor reaches 75% of full speed. |
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Term
| What is the difference between a current and potential relay? |
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Definition
| The method of control of the relays and their contact position. |
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Term
| The contacts of the current relay are _______. |
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Definition
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Term
The controlling factor for a potential relay is ___________.
a. back electromotive force
b. line voltage
c. voltage drop
d. none of the above |
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Definition
| a. back electromotive force |
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Term
| T/F: The contacts of the potential relay are normally open |
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Definition
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Term
What is the approximate speed at which the starting windings or components should be removed from the motor electrical circuit?
a. 50%
b. 75%
c. 90%
d. 100% |
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Definition
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Term
As a single-phase motor's speed is increase from a stationary position, the current draw _________.
a. increases
b. decreases |
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Definition
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Term
As a single-phase motor's speed is increased from a stationary position, the back electromotive force _______.
a. increases
b. decreases |
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Definition
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Term
which of the following statements reflects the correct terminal identification of a potential relay?
a. 1&2 coil, 2&4 contacts
b. 2&4 coil, 3&6 contacts
c. 1&5 coil, 2&5 contacts
d. 2&5 coil, 1&2 contacts |
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Definition
| d. 2&5 coil, 1&2 contacts |
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Term
A G.E. potential relay with the number 3ARR3-D4F6 would have a continuous coil voltage of ______.
a. 214
b. 332
c. 420
d. 502 |
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Definition
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Term
An RBM potential relay with the number 128-122-2324K would have a continuous coil voltage of _______.
a. 120
b. 170
c. 256
d. 336 |
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Definition
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Term
A G.E. potential relay with a number 3ARR3-C3A1 could be replaced with which of the following RBM potential relays?
a. 128-212-1167AB
b. 128-112-1161AB
c. 128-151-1111CD
d. 128-212-1147AB |
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Definition
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Term
An RBM potential relay with a number 128-122-1161BC could be replaced with which of the following G.E. potential relays?
a. 3ARR3-C4B2
b. 3ARR3-C9D2
c. 3ARR3-C6B2
d. 3ARR3-C2B2 |
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Definition
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Term
| What are two type of bearing used in the industry? |
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Definition
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Term
which of the following is not an advantage of the ball bearings?
a. more efficient than a sleeve bearing
b. requires less maintenance than a sleeve bearing
c. cheaper than a sleeve bearing
d. longer life than a sleeve bearing |
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Definition
| c. cheaper than a sleeve bearing |
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Term
What is the main reason that sleeve bearings are used in the industry?
a. cost
b. maintenance
c. life
d. efficiency |
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Definition
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Term
| what is a direct drive application? |
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Definition
| When a motor is connected directly to the device that is providing rotation |
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Term
| How is direct-drive application used in the industry? |
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Definition
| A direct-drive application is used when the motor is attached directly to the device requiring rotation |
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Term
| Why are V-belts popular in the industry? |
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Definition
| V-belts are an economical methods of transferring rotating motion to a device |
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|
Term
| What is the correct tension on a V-belt |
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Definition
| A depression of 1" on a V-belt |
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Term
| T/F: If the starting relay is working properly, there will be no ampere draw through the starting circuit after the motor reaches full speed. |
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Definition
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Term
| What is the purpose of a hard-start kit in conjunction with a hermetic compressor? |
|
Definition
| To modify a PSC motor into a CSR motor |
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Term
| What electrical components make up a hard-start kit? |
|
Definition
| Starting capacitor and potential relay |
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Term
| Name the three ways in which ball bearings may be lubricated |
|
Definition
| permanently lubricated, packed lubrication, and grease fittings |
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|
Term
| T/F: over lubrication of a motor and its bearings is as damaging as under lubrication |
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Definition
|
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Term
| name three ways in which sleeve bearings may be lubricated |
|
Definition
| oil wick, yarn-packed, and oil ring |
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Term
| what are the common sizes of V-belts and what are there applications? |
|
Definition
3/8" fractional horsepower applications
1/2"/1-hp to 5-hp
21/32"/ when motor pulley is larger than 5" |
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Term
what is compressor speed of an open-type compressor if the motor rpm is 1,750, the motor pulley diameter is 4 inches, and the pulley diameter of the compressor is 16 inches
a. 438
b. 468
c. 498
d. 528 |
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Definition
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Term
what size motor pulley would be required if the motor turns 1,750 rpm, the fan pulley is 8 inches, and the desired rpm of the fan is 650?
a. 3
b. 4
c. 5
d. 6 |
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Definition
|
|
Term
| what is one situation in which a ball bearing cannot be used? |
|
Definition
| sealed hermetic compressors |
|
|
Term
| explain the operation of a solid-state PTC starting relay |
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Definition
| a ceramic material resistance increases as it heats up when current passes through it, causing the relay to open |
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Term
| what advantages does the solid-state starting relay have over the convention current-type relay? |
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Definition
| the solid-state starting relay cover several different size applications |
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Term
Start of chpt. 11
which of the following is the largest electrical load in an AC or refrigeration system?
a. evaporator fan motor
b. condenser fan motor
c. compressor
d. relay coil |
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Definition
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Term
which of the following is the major difference between a relay and a contactor?
a. ampacity rating
b. number of contacts
c. mechanical linkage
d. relay coil |
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Definition
|
|
Term
| what is the major difference between a magnetic starter and a contactor? |
|
Definition
| a magnetic starter has overloads protection, while a contactor does not |
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|
Term
| what is the purpose of a contactor or relay? |
|
Definition
| to control a loads with the supervision of some type of switch |
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|
Term
| explain the operation of a contact5or and a relay |
|
Definition
| when the correct voltage is applied to the relay or contactor coil, the contacts will close |
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|
Term
| what are the two types of armatures used in contactors and relays? |
|
Definition
|
|
Term
| what are the three major parts of a contactor or relay? |
|
Definition
| coil, contacts, and mechanical linkage |
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|
Term
| what is the proper procedure for checking the coil of a contactor or relay? |
|
Definition
| check the coil with an ohmmeter |
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Term
| contacts are usually made of _____. |
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Definition
| silver or cadmium attached to a copper base |
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Term
| what are the major reasons for replacing the contacts of a contactor? |
|
Definition
| when they are burned or pitted and a voltage drop exists across the contacts |
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Term
a contactor or relay coil could be electrically diagnosed in which of the following conditions?
a. open
b. shorted
c. good
d. all of the above |
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Definition
| d. all of the above (open, shorted, good) |
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Term
| T/F: a voltage reading taken across closed contacts of the same pole will show the voltage drop across the contacts |
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Definition
|
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Term
| the easiest faults to diagnose with a contactor are usually problems with the _____. |
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Definition
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Term
| why is it difficult to repair a contactor? |
|
Definition
| the availability of parts and cost |
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Term
| what do the terms 'normally open' and 'normally closed' mean in reference to relays and contactors? |
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Definition
| the position of the contacts when the device is de-energized, normally open are open and normally closed are closed |
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Term
| T/F: the contacts in a relay are easily checked by a visual inspection |
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Definition
|
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Term
| T/F: the size of the relay coil is smaller than the contactor coil |
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Definition
|
|
Term
| what is the purpose of an overload? |
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Definition
| to protect a load from overcurrent |
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|
Term
an electric heater is a(n)________ load
a. resistive
b. inductive |
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Definition
|
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Term
an electric motor is a(n)_______ load
a. resistive
b. inductive |
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Definition
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Term
which of the following is the simplest overload used in the industry?
a. pilot duty
b. line break
c. fuse
d. magnetic |
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Definition
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Term
the line break overload breaks _________
a. the control circuit
b. the power voltage to the load
c. the fuse element
d. non of the above |
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Definition
| b. the power voltage to the load |
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|
Term
the pilot duty overload breaks_______
a. the control circuit
b. the power voltage to the load
c. the fuse element
d. none of the above |
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Definition
|
|
Term
| how does the line break overload operate? |
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Definition
| the current draw produces heat on a bimetal which causes the bimetal to warp and open the contacts |
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Term
| T/F: the most popular line break overload used in small equipment is the two-wire klixon overload. |
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Definition
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|
Term
which of the following types of overloads gives the fastest response time to an overload condition?
a. magnetic
b. current
c. line break
d. electronic |
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Definition
|
|
Term
| what is the advantage of an internal compressor overload? |
|
Definition
|
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Term
| what is the proper procedure for checking an internal compressor overload? |
|
Definition
| make sure the compressor is cool to the tough and make an ohm reading between common and start, common and run, and run and start. If there is a reading between run and start, and no reading between common and start and common and run the internal overload is open. |
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Term
| name two basic types of pilot duty overloads and describe how they operate |
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Definition
| current type/current draw of load is transferred to heat and opens a set of contacts; magnetic type/current draw of load is transferred to magnetism, which opens a set of contacts. |
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Term
| what is a magnetic starter? |
|
Definition
| a device that controls a load and provides overload protection |
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|
Term
| T/F: magnetic starters are primarily used on single-phase motors |
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Definition
|
|
Term
| what are the three types of overloads used in magnetic starters in the industry? how does each type work? |
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Definition
| bimetal relay, thermal relay, and molten relay. bimetal relay and thermal relay sense temperature and open a set of contacts on overload. the molten alloy heats and if overload occurs the molten alloy will melt and open a set of contacts |
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Term
| T/F: push button stations are widely used in the industry |
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Definition
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|
Term
| what characters of the current draw of an electric motor from locked rotor (start) until the motor reaches full speed |
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Definition
| the current draw of a motor from a stationary position is from high to low |
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Term
start of chpt 12
what is the purpose of a thermostat in a control system? |
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Definition
| a thermostat is designed to stop and start loads in a system to maintain a specific temperature |
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Term
which of the following are the two main types of thermostats?
a. low-voltage and pilot duty
b. line-voltage and high-voltage
c. low-voltage and line-voltage
d. low-voltage and high-voltage |
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Definition
| c. low-voltage and line-voltage |
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Term
a heating thermostat opens on a ____.
a. rise in temperature
b. fall in temperature |
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Definition
|
|
Term
a cooling thermostat opens on a ____.
a. rise in temperature
b. fall in temperature |
|
Definition
|
|
Term
| explain the operation and application of a remote bulb thermostat |
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Definition
| a remote bulb thermostat is one that has the controlling element located in a remote position, with a small copper tube connecting the bulb to the main body of the thermostat. |
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|
Term
| T/F: a bimetal is a combination of two pieces of metal that are welded together, each with a different coefficient of expantion |
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Definition
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|
Term
| why should a thermostat be snap acting? |
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Definition
| to prevent the contacts from arching |
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|
Term
which of the following methods are used to ensure snap action of low-voltage thermostat elements?
a. mercury bulbs and small permanent magnets
b. small permanent magnets and springs
c. springs and solenoids
d. solenoids and mercury bulbs |
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Definition
| a. mercury bulbs and small permanent magnets |
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Term
| T/F: the line-voltage thermostat is more common in commercial applications than the low-voltage thermostat. |
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Definition
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|
Term
low-voltage thermostats would be used for which of the following applications?
a. residitual AC control systems
b. refrigerator thermostats
c. window unti thermostats
d. all of the above |
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Definition
| a. residential AC control systems |
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Term
| what are the major differences between the line- and low-voltage thermostats |
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Definition
| the line-voltage thermostat is not as accurate because of the size of the bimetal that must be used and generally has only one function, while the low-voltage thermostat is more accurate and often has more than one function |
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Term
| what modes of operation do the letter designations R,Y, Y1, Y2, W, W1, W2, and G represent in a low-voltage thermostat? |
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Definition
| R-transformer power; Y-cooling function; Y1-first stage cooling; Y2-second stage cooling; W-heating function; W1-first stage heating; W2-second stage heating; G-fan function |
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|
Term
| what is the purpose of a heating anticipator? |
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Definition
| a heating anticipator is used to anticipate hat in order to compensate for system lag and overshoot |
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Term
| what is the proper procedure for troubleshooting thermostats? |
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Definition
| troubleshooting a thermostat can be performed by making a resistance check of the thermostat. the technician must know what position the thermostat should be in. |
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Term
the temperature difference between the closing of the thermostat and the time when warm air begins to reach the thermostat is called____.
a. overshoot
b. heat anticipation
c. system lag
d. system lead |
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Definition
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Term
the temperature difference between the opening of the thermostat and the time when the warm air no longer delivered to the room is called _____.
a. overshoot
b. heat anticipation
c. system lag
d. system lead |
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Definition
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Term
the overshoot and system lag can produce an additional temperature swing of as much as _____.
a. 2 degrees F
b. 5 degrees F
c. 10 degrees F
d. 20 degrees F |
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Definition
|
|
Term
| what is the purpose of staging heating and cooling equipment? |
|
Definition
| the staging thermostat controls more than one section of heating and cooling |
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Term
| why are two-stage heating thermostats used on heat pumps |
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Definition
| the first stage heat is used for the compressor operation and the second stage is used for supplementary heat of the compressor does not adequately heat the structure |
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Term
| what is the purpose of a low-pressure switch? |
|
Definition
| a low-pressure switch is designed to stop the compressor if the suction pressure is dangerously low. |
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|
Term
| what is the purpose of a high-pressure switch? |
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Definition
| a high-pressure switch is designed to stop the compressor if the discharge pressure reaches an unsafe condition |
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Term
| T/F: a step-down transformer is used to boost voltage |
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Definition
|
|
Term
| what is the correct procedure for checking transformers? |
|
Definition
| the correct method to check transformers is to make a resistance check of both windings or to check the voltage output if the correct primary voltage is applied |
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Term
how is a transformer sized or rated>
a. primary volts
b. secondary volts
c. voltamperes
d. all of the above |
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Definition
|
|
Term
| what precaution should be taken when replacing transformers? |
|
Definition
| the correct size transformer should be used when replacing a transformer. |
|
|
Term
| what is the purpose of a humidistat? |
|
Definition
| to open and close a set of contacts according to the humidity |
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|
Term
the oil safety control is a differential pressure switch and operates on when two pressures?
a. oil pressure and suction pressure
b. oil oressure and discharge pressure
c. suction pressure and discharge pressure
d. none of the above |
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Definition
| a. oil pressure and suction pressure |
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Term
| time-delay relays are sued in heating, cooling and refrigeration systems to _________. |
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Definition
| delay the starting of a load |
|
|
Term
| give several reasons for using a time clock inn the heating and cooling industry |
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Definition
| a time clock is used in the HVAC industry to cut off or on a system or component at a particular time |
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Term
| why is it important for service technicians to understand the operation of any electric component in the system? |
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Definition
| to be able to troubleshoot the component |
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|
Term
| what is the purpose of a clock thermostat? |
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Definition
| a clock thermostat is used to set back or up the temperature of a structure at a particular time |
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|
Term
| what is a multisetback clock thermostat? |
|
Definition
| the multisetback time clock has more than two periods of set up and back |
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|
Term
| how is the clock portion of a clock thermostat powered? |
|
Definition
|
|
Term
| explain the difference between single-setback and multi-setback clock thermostat |
|
Definition
| a single-setback clock thermostat has a limited number of set up and set back periods in a day, while the mulit-setback clock thermostat would have more options |
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|
Term
| what routine maintenance should be performed on a thermostat controlling residential heating and cooling? |
|
Definition
| cleaning of the bi-metal element |
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|
Term
| what is the calibration with respect to a thermostat? |
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Definition
| setting the thermostat to open and close at the correct temperature |
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|
Term
| what is the purpose of the fan switch on a residential low-voltage thermostat? |
|
Definition
| to operate the fan without the cooling or heating operating |
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|
Term
| why are the advantages of using digital thermostats? |
|
Definition
| the digital thermostat is more accurate, more versatile, easier to read, and multifunctional |
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|
Term
| why are communicating control systems becoming increasingly popular? |
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Definition
| communicating thermostats populatiry had come from the availability of wireleaa networks, and the advancements of wireless equipment. |
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|
Term
how many wires are used by communicating controls systems to connect to the components?
a. 1
b. 2
c. 4
d. 8 |
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Definition
|
|
Term
| T/F: digital thermostats sense the temperature of the structure by use of sensors |
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Definition
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Term
start of chpt 13
what is the advantage of using solid-state devices in electronic control systems? |
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Definition
| the transistor is smaller and has greater durability |
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Term
semiconductors are _____.
a. conductors
b. insulators
c. half conductors
d. none of the above |
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Definition
|
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Term
diodes and rectifiers allow current to_____
a. flow in one direction only
b. flow in both directions
c. divide paths of flow
d. none of the above |
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Definition
| a. flow in one direction only |
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Term
| what is the difference between a diode and a rectifier |
|
Definition
|
|
Term
a thermistor is a resistor that changes resistance with ______
a. pressure
b. sound
c. light
d. temperature |
|
Definition
|
|
Term
| what are the two types of thermistors? |
|
Definition
| thermistor and vaistor; thermistor's resistance decreases as the temperature increases, and the varistor's resistance decreases with an increase in voltage. |
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|
Term
| what materials are used to make semiconductors? |
|
Definition
| half conductors; germanium or silicon |
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Term
|
Definition
| an electronic device that is composed of n-type or p-type materials and is used as a switch or to amplify a signal |
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|
Term
the transistor is used ______
a. as a signal
b. to amplify a signal
c. both a and b
d. none of the above |
|
Definition
|
|
Term
| what is the difference between a one function and a multifunction electronic control device? |
|
Definition
| a one function electronic control device has one function while a multifunction electronic control device would have more than one function |
|
|
Term
| what is the purpose of an anti-short cycling device? |
|
Definition
| it prevents the compressor from rapidly stopping and starting |
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|
Term
| T/F: the conductivity of materials plays an important part in the action of semiconductors |
|
Definition
|
|
Term
| how have electronic control modules affected the control circuits for heat pumps and fossil fuel furnaces? |
|
Definition
| many solid-state modules are being used in the industry today to control the operation of furnaces and heat pumps |
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|
Term
solid-state timers can_______
a. delay on opening contacts
b. delay on closing contacts
c. have an adjustable delay
d. all of the above |
|
Definition
| d. all of the above (delay on opening contacts, delay on closing contacts, and have an adjustable relay) |
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|
Term
a semiconductor assist kit is used on a _____
a. PSC motor
b. shaded-pole motor
c. three-phase motor
d. all of the above |
|
Definition
|
|
Term
| T/F: the repair of electronic control modules is often accomplished by the charging of individual electronic components on a circuit board. |
|
Definition
|
|
Term
| what is the basic troubleshooting procedure sued to diagnose a multifunction electronic control module |
|
Definition
| look a the input and output signals and determine if the operation of the system is correct |
|
|
Term
which of the following components are used for flame detection in a residential oil-fire furnace?
a. thermocouple
b. flame rod
c. cad cell
d. none of the above |
|
Definition
|
|
Term
| T/F: the technician must know the input signals to an electronic module to be able to determine what the output signals should be. |
|
Definition
|
|
Term
| what are the functions of a gas furnace electronic control board? |
|
Definition
| pilot safety, lockout in the event of flame failure, prepurge; post purge; blower motor operation; diagnostics |
|
|
Term
| why are electronic control modules used on modern gas furnaces and heat pumps? |
|
Definition
| they produce a more efficient and safer system |
|
|
Term
which of the following is the most popular medium used to transfer heat from the heating appliance to the conditioned area of a residential structure?
a. air
b. water
c. steam
d. none of the above |
|
Definition
|
|
Term
which of the following types of heating systems is most popular in the commercial and industrial section of the industry?
a. air
b. water
c. steam
d. none of the above |
|
Definition
|
|
Term
| how is the heat transfer from the heating appliance to the conditioned space accomplished in a residential warm-air furnace? |
|
Definition
|
|
Term
| what methods are used to remove the produces of combustion from the combustion chamber of a heating appliance using a fossil fuel source? |
|
Definition
|
|
Term
| T/F: an electric furnace requires a vent from the heat exchanger |
|
Definition
|
|
Term
which of the following is not a common method used to start the blower motor in a forced-air furnace?
a. temperature
b. time and temperature
c. time
d. pressure |
|
Definition
|
|
Term
| what is the purpose of the fan switch in a warm-air furnace? |
|
Definition
| to start and stop the blower motor when the temperature is correct |
|
|
Term
| explain the operation of three types of fan switches used in the industry |
|
Definition
temperature-starts and stops the blower motor when the temperature is correct
time-time controlled fan switch starts and stops the blower motor by a timed function
time and temperature- uses a combination of time and temperature fan switches |
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|
Term
what is the result of the following conditions in regard to the operation of a fan switch in a furnace?
a. fan switch setting too low
b. fan switch setting too high |
|
Definition
a. cold drafts in the structure
b. furnace gets too hot; air is too hot |
|
|
Term
| what is the purpose of a limit switch in a warm-air furnace? |
|
Definition
| it opens if the temperature of the furnace gets too high and removes the heat source |
|
|
Term
| T/F: the standing pilot is a continuous flame that is located near the burner and can easily ignite the main burner. |
|
Definition
|
|
Term
and intermittent pilot ignites when the ___
a. thermostat is set to "heat"
b. thermostat calls for heat
c. manual pilot valve is opened
d. main gas valve opens |
|
Definition
| b. thermostat calls for heat |
|
|
Term
which component is most commonly used to prove that a standing pilot is lit?
a. bi-metal element
b. thermostat
c. thermocouple
d. none of the above |
|
Definition
|
|
Term
how are most intermittent pilots lit?
a. manually
b. glow coils
c. heat
d. spark |
|
Definition
|
|
Term
| what is a typical operational sequence of an intermittent pilot burner control system? |
|
Definition
| the ignition control lights the pilot first, proves the pilot, and then opens the main gas valve, which lights from the pilot |
|
|
Term
| T/F: a thermocouple is strong enough to close the pilot safety solenoid in a gas valve |
|
Definition
|
|
Term
| what is the purpose of a gas valve? |
|
Definition
| the gas valve directs the flow of gas to the burner when energized |
|
|
Term
| what is a redundant gas valve? |
|
Definition
| a redundant gas valve has tow auto and one manual gas valves in one |
|
|
Term
how many valve could be incorporated in a redundant-type gas valve?
a. one
b. two
c. three
d. four |
|
Definition
|
|
Term
which of the following are the two types of ignition used with direct ignition?
a. spark and glow coil
b. spark and hot surface
c. spark and thermocouple
d. thermpcouple and glow coil |
|
Definition
|
|
Term
most hot surface ignition devices are made of _____
a. silicon
b. crystallized sulfur
c. silicon-coated steel
d. silicon sulfide |
|
Definition
|
|
Term
| what is a typical operation sequence of a direct ignition pilot control system? |
|
Definition
| the main burner ignites from the ignition source |
|
|
Term
| what is the function of an oil burner primary control? |
|
Definition
| the oil burner ignites from the ignition source |
|
|
Term
which of the following is not a component of a gun type atomizing oil burner?
a. burner motor
b. oil pump
c. ignition electrodes
d. thermocouple |
|
Definition
|
|
Term
| what are the two types of primary controls used to supervise the operation of an oil burner? |
|
Definition
| stack switch and cad cell |
|
|
Term
which of the following devices uses light to prove the flame of an oil burner?
a. silicon sulfide cell
b. cad cell
c. photo cell
d. none of the above |
|
Definition
|
|
Term
| T/F: a stack switch uses pressure to rove the flame of an oil burner |
|
Definition
|
|
Term
what is the approximate resistance reading of a cad cell viewing a properly adjusted oil burner flame?
a. 300 to 1,000 ohms
b. 1,000 to 1,300 ohms
c. 1,500 to 2,000 ohms
d. over 2,000 ohms |
|
Definition
|
|
Term
| where does the stack switch primarily control pick u the signal that a flame has been proven? |
|
Definition
|
|
Term
| explain the operation of a cad cell primary control |
|
Definition
| the cad cell sees the oil burner flame and allows the burner to keep operating; if the flame is not correct, the control will lock out the oil burner |
|
|
Term
| explain the operation of a stack switch primary control |
|
Definition
| the stack switch senses that the oil burner has ignited by the temperature of the stack |
|
|
Term
| T/F: the ignition transformer is always energied as long as the thermostat is calling for heat |
|
Definition
|
|
Term
| where is a stack switch mounted in the oil burner system? |
|
Definition
|
|
Term
| what is the correct location of a cad cell? |
|
Definition
| should be in the burner to be with a good view of the oil burner flame |
|
|
Term
| what type of control is commonly used as an operating control in a hydronic system?` |
|
Definition
|
|
Term
| what type of control is commonly used as an operating control for a steam boiler? |
|
Definition
|
|
Term
start of chpt 15
what is the first step in trouble shooting any system or component? |
|
Definition
| checking the power supply |
|
|
Term
open-type electric motors will fail in which of the following three areas?
a. windings, bearings, and centrifugal switch
b. windings, bearings, and contactor
c. windings, centrifugal switch, and contactor
d. centrifugal switch, contactor, and mobile module |
|
Definition
| a. windings, bearings, and centrifugal switch |
|
|
Term
electric motor windings fail in which of the following conditions?
a. open
b. shorted
c. grounded
d. all of the above |
|
Definition
| all of the above (open, short, and grounded) |
|
|
Term
| how can bearing failure be determined in a hermetic compressor motor? |
|
Definition
| current draw, noise, and seized |
|
|
Term
| T/F: the best way to check the contacts of a contactor is by visual inspection |
|
Definition
|
|
Term
| in troubleshooting contacots and relays, three areas must be checked: |
|
Definition
a. contact
b. coil
c. mechanical |
|
|
Term
| how do you make a voltage check to diagnose the condition of a set of contacts in a relay or contactor? |
|
Definition
| check across the contacts; if the voltage is being read then that is the amount the contact is loosing |
|
|
Term
what is the major cause of a contact misalignment?
a. coil failure
b. pitted contacts
c. faulty mechanical linkage
d. none of the above |
|
Definition
| c. faulty mechanical linkage |
|
|
Term
if the coil of a relay is shorted, the resistance reading will be _______ ohms
a. 0
b. 500
c. 10,000
d. infinite |
|
Definition
|
|
Term
if the coil relay is open, the resistance reading will be_________ ohms
a. 0
b. 500
c. 10,000
d. infinite |
|
Definition
|
|
Term
|
Definition
| with and ohmmeter or voltmeter |
|
|
Term
| how do you check a circuit breaker? |
|
Definition
| check the switch position and what current draw it will open |
|
|
Term
| when a line voltage overload is weak, an amperage check should be made to see what ______ is causing the overload to open |
|
Definition
|
|
Term
| T/F: the internal overload is difficult to check because it is in parallel with the common terminal of the compressor |
|
Definition
|
|
Term
| what precaution should a service technician take when diagnosing the condition of an internal overload in a hermetic compressor? |
|
Definition
| that the internal overload is in the closed position |
|
|
Term
| T/F: the low voltage thermostat is easier to troubleshoot than the line-voltage thermostat |
|
Definition
|
|
Term
the line-voltage thermostat usually has _____ functions
a. 1
b. 2
c. 3
d. multiple |
|
Definition
|
|
Term
| give some common applications for the line and low-voltage thermostats |
|
Definition
Line: refrigerators, freezers, ice makers, water coolers, window units
Low: residential AC units, Some light commercial AC units |
|
|
Term
| what do the letters R, Y, G, and W represent on a thermostat |
|
Definition
R: power from tranformer
Y: cooling function
G: fan function
W: heat function |
|
|
Term
| How do you diagnose a bad pressure switch? |
|
Definition
| by making a resistance or a voltage check of the switch at a known pressure |
|
|
Term
| the most important aspect of checking a pressure switch is to understand its _______ in the system |
|
Definition
|
|
Term
| what is the proper procedure for checking a transformer? |
|
Definition
| by making a resistance or voltage check |
|
|
Term
what thermostat is used in a force-air furnace to start and stop the blower motor?
a. limit switch
b. fan switch
c. combination switch
d. none of the above |
|
Definition
|
|
Term
| list three uses of limit switches in a forces-air furnace. |
|
Definition
roll-out switches
high limit switches
limit switches |
|
|
Term
what is the millivolt reading of a good thermocouple?
a. 5 mV
b. 18 mV
c. 50 mV
d. 120 mV |
|
Definition
|
|
Term
| what procedure is used to check a combination gas valve? |
|
Definition
| the pilot and main solenoid should be checked |
|
|
Term
the combination gas valve gas ____ valves
a. 1
b. 2
c. 3
d. 4 |
|
Definition
|
|
Term
what should be the first check a tecnician should make when troubleshooting ignition modules?
a. voltage across gas valve terminals on module
b. spark across igniter/sensor gap
c. good ground connections
d. power supply to module |
|
Definition
| d. power supply to module |
|
|
Term
| T/F: the spark on an intermittent pilot ignition system sparks the entire call for heat cycle of a gas warm-air furnace |
|
Definition
|
|
Term
| what is the difference between spark ignition and hot surface ignition? |
|
Definition
spark lights burner by spark
hot surface lights by heated surface |
|
|
Term
| the resistance of the cad cell (increases/decreases) when the cell views a correctly adjusted oil burner flame |
|
Definition
|
|
Term
the stack switch uses which of the floowing methods to determine combustion in an oil-fired furnace?
a. sight
b. pressure
c. heat
d. none of the above |
|
Definition
|
|
Term
| how would you troubleshoot a stack switch and cad cell primary control? |
|
Definition
| troubleshoot each by observation when a call for heat occurs, then by proper voltage and resistance checks |
|
|
Term
| what is the purpose of a roll-out switch |
|
Definition
| designed to interrupt the fossil fuel supply if the flame rolls out of the combustion chamber |
|
|
Term
start of chpt 16
what is the purpose of and air-conditoning control system? |
|
Definition
| to supervise the loads in an AC system |
|
|
Term
which of the following components is in a typical condensing unit?
a. compressor
b. condenser
c. condenser fan motor
d. all of the above |
|
Definition
| d. all of the above (compressor, condenser, condenser fan motor) |
|
|
Term
most residential condensing units require a control voltage of ______
a. 24 volts
b. 120 volts
c. 240 volts
d. none of the above |
|
Definition
|
|
Term
safety controls used for a condensing unit would be wired in ______ with the contactor coil.
a. series
b. parallel |
|
Definition
|
|
Term
the condenser fan motor and compressor in a residential condensing unit are generally wired in ________
a. series
b. parallel |
|
Definition
|
|
Term
a packaged AC unit is build _________
a. with all components housed in one unit
b. with the evaporator
c. with the compressor in a separate compartment
d. none of the above |
|
Definition
| a. with all components housed in one unit |
|
|
Term
|
Definition
| a packaged unit utilizing electric AC and gas heat |
|
|
Term
| T/F: the simplest control operation on a condensing unit is a contacter. |
|
Definition
|
|
Term
| explain the operation of a condensing unit |
|
Definition
| takes low pressure super heated refrigerant from the evaporator and supplies sub cooled liquid refrigerant back to the evaporator |
|
|
Term
| what is a split AC system? |
|
Definition
| a conditioned air system that has 2 parts: 1- a condensing unit and 2- and air source with an evaporator |
|
|
Term
which of the following would not be used to supply the air for a split-system AC installation?
a. condensing unit
b. oil furnace
c. gas furnace
d. fan-coil unit |
|
Definition
|
|
Term
what kind of heat could be added to an air-cooled packaged unit for the unit to supply heat to a structure?
a. heat pump
b. fossil fuel
c. electrical resistance heat
d. none of the above |
|
Definition
| c. electrical resistance heat |
|
|
Term
which of the following types of units would be used to condition a small light commercial building and would be installed on the roof?
a. split system
b. condensing unit
c. fan-coil unit
d. packaged unit |
|
Definition
|
|
Term
which of the following items would not be used in heat pump?
a. defrost control
b. contactor
c. indoor fan motor
d. gas valve |
|
Definition
|
|
Term
which of the following applications would require supplementary heat?
a. gas furnace
b. oil furnace
c. heat pump
d. all of the above |
|
Definition
|
|
Term
on an AC split-system installation, the two parts of the system that require power connections are the ______ and _______
a. furnace and condensing unit
b. indoor blower motor and condensing unit
c. fan-coil unit and condensing unit
d. all of the above |
|
Definition
| d. all of the above (furnace, condensing unit, indoor blower motor, and fan-foil unit) |
|
|
Term
field wiring is installed by ______
a. assembly line personnel
b. installation technicians
c. service technicians
d. all of the above |
|
Definition
| b. installation technicians |
|
|
Term
| T/F: electrical resistance heat is commonly used in residential applications |
|
Definition
|
|
Term
| what are two major considerations an installation technician must take into account when installing air-conditioning power wiring? |
|
Definition
1- the length of the conductor
2- the amperature required by the equipment |
|
|
Term
what type of control system is used on most residential air conditioning power wiring?
a. line voltage
b. low voltage
c. both a and b |
|
Definition
|
|
Term
| what is the purpose of control wiring? |
|
Definition
| to interconnect the wires to the control unit |
|
|
Term
how many power supplies would be required for a split system using electric resistance heat as the heating source?
a. 1
b. 2 |
|
Definition
|
|
Term
what does terminal "O" on a heat pump thermostat control?
a. contactor
b. compressor
c. indoor fan motor
d. reversing valve |
|
Definition
|
|
Term
what type of AC system could use a closet space for installation?
a. packaged unit
b. split system |
|
Definition
|
|
Term
| T/F: the outdoor fan motor is de-energized on a heat pump during the defrost cycle. |
|
Definition
|
|
Term
| why are customer relations important to the technician |
|
Definition
| so the customer is treated fairly and with respect |
|
|
Term
what is the purpose of using supplementary heat on a heat pump?
a. heat the supply air during the defrost cycle
b. assist the heat pump in heating the structure in extremely low ambient conditions
c. have a source of heat if or when the heat pump is inoperable
d. all of the above |
|
Definition
|
|
Term
the thermostat on a residential conditioned air split system would connect directly too _______
a. terminal board in air handler or furnace
b. condensing unit
c. gas valve
d. indoor fan relay |
|
Definition
| a. terminal board in air handler or furnace |
|
|
Term
which of the following tasks should a tachnician do when performing a check, tech, and start procedure on a new installation?
a. check all electrical connections for tightness
b. check the voltage input to the equipment
c. check the current draw of the compressor
d. all of the above |
|
Definition
|
|
Term
| what is the difference between a two-wire and three-wire damper motors? |
|
Definition
a two wire damper motor is returned to normal position manually with a spring
a three-wire damper motor is opened and closed by voltage |
|
|
Term
| how does a two-wire damper motor return to its original position? |
|
Definition
| returned to normal position manually with a spring |
|
|
Term
start of chpt 18
what is the most common switch used in AC control systems?
a. pressure
b. thermostat
c. push button
d. humidistat |
|
Definition
|
|
Term
| the _____ is the most important load in a refrigeration system |
|
Definition
|
|
Term
| why is it important for a service technician to be able to use volt-ohm meters? |
|
Definition
| to be able to troubleshoot |
|
|
Term
a pictoral or component arrangement diagram shows_______
a. the components in a circuit by circuit arrangement
b. the installation connections only
c. the control panel layout
d. all of the above |
|
Definition
| c. the control panel layout |
|
|
Term
| how does process of elimination play a part in troubleshooting an AC system? |
|
Definition
| many electrical components can be eliminated by observing the operation of the unit |
|
|
Term
| why is hopscotching an important tool when troubleshooting? |
|
Definition
| hopscotching is a method of checking the switches in an electrical circuit |
|
|
Term
| why are wiring diagrams an important tool when troubleshooting AC systems? |
|
Definition
| they show the component layout in the electrical panel, tell how the unit should be operating, and break down the control system into a circuit-by-circuit arrangement |
|
|
Term
which of the following could be problems if the compressor wont start?
a. blown fuse'
b. contactor
c. thermostat
d. all of the above |
|
Definition
|
|
Term
which of the following could be the problem if the compressor will not runn by the condenser fan motor will operate? how can we fix it?
a. bad run capacitor
b. bad condenser fan motor capacitor
c. bad contactor
d. none of the above |
|
Definition
| a. bad run capacitor, fix it by replacing the compressor running capacitor |
|
|
Term
which of the following could be the cause of the compressor cycling on overload on heating?
a. bad contactor coil
b. defective outdoor thermostat
c. damaged reversing valve
d. none of the above |
|
Definition
| c. damaged reversing valve |
|
|
Term
which of the following could be a reason for the compressor not to run?
a. loose electrical connections
b. compressor internal overload open
c. lock-down compressor
d. all of the above |
|
Definition
|
|
Term
| why is it important for a technician to be able to use a clamp-on ammeter? |
|
Definition
| in order to read the current of an electrical circuit |
|
|
