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                                                             HVAC Test

                                                                                             General HVAC  Practice Exam   

Multiple Choice

Identify the choice that best completes the statement or answers the question.

 1. A technician is servicing a 240V AC split system that has pitted condenser contacts which are causing the compressor to draw a larger amp draw then usual. Which of the following multimeter readings would probably indicate this?

a.

238 VAC across the T1 and T2 terminals.

  b.

208 VAC across the compressor terminals.

c.

240 ohms across the L1 to T1 terminals.

  d.

240 amps across the compressor fan motor.


 2.  A PTC thermistor designed into a hermetic compressor  refrigerator start-up system will be in what condition 5 minutes after freezer defrost begins.

a.  its low resistance state.                                                     b. its high resistance state.

c.  switched to its capacitor run state.                                   d. deactivated defrost relay state.

 

3. 2,771 BTUs is equal to _______ .

a.

100 PSI

b.

100 WC

c

812w

d.

812kw


4. Left over moisture remaining in a system after evacuation

a.

will be removed by the drier

b.

can be removed by nitrogen.

c.

should be blown out with air.

d.

will drain out through the moisture condensation pipe.


5. A dual capacitor has 3 terminals marked Herm, Fan, Common,  and a red dot on top. L1 is connected to the L1 contactor terminal,  L2 is connected to the compressor common wire terminal. Which terminal should the red dot be near?                                                                                                                                

a. Herm.                                                                                  b. Fan. 

c. Common                                                                            d.  It does not matter, it represents its micro farad code value.

 

6. When measuring AC voltage across a compressor motor with an AC multimeter, you are actually measuring the

a. AC peak voltage value                                                      b. root means square value 

c. impedance value                                                               d. the rectified voltage value

 

7.  The pressure switch in an induced draft motor furnace will be in what state if you have a short across the r and w terminals in the thermostat and the furnace is operating properly.

a. open state                                                                          b. closed state    

c. hibernation state                                                               d. vacuum state

 

8. A technician working on a heat pump with a complaint of not enough heat with an OAT of 55 degrees, finds a delta t of 45 degrees across the indoor coil with a return air temp of 60 degrees. What could be the problem?

a. fan blower speed.                                                            b.  reversing valve stuck in ac mode.   

c. totally blocked indoor check valve                                 d. nothing is wrong, this is how a heat pump works.

 

9.  A new install for a AC split system was just completed. A 4 ton system, 4 pounds of r410a,  dual capacitor, THX valve,  240vlts 1/2hp, 16.1 FLA motor, 14awg  wiring  for the compressor, 18awg for the t-stat, 1/2 inch line-set, digital set back 24vlt T-stat.  On start up the system works for 5 minutes before the  breaker trips and the compressor is extremely hot. System does not function after resetting breaker. What could cause this problem? 

a. all residential systems need r22.                                  b. thermostat r terminal shorted out to the y terminal.  

c. compressor wiring to small.                                           d. need larger compressor motor for r410 high pressure. 

 

10. The formula for calculating electrical power is

a.   E X I               b.   E squared / R                                    c.     I squared x R            d.     All of the above

 

11. Placing a 20uf capacitor in series on a split phase motor with the start winding will


a. Short out because of the small uf value.                    b. Increase compressor motor torque.      

c.  Not work because you can only have a start capacitor in the start winding.   

d. Make a capacitor start, induction run motor.

 

12.  An oil burner common operating pressure is

a. 100 IWC                            b. 100 PSIA                   c. 100 PSIG                      d. 100MG

 

13. On a capillary tube system, superheat at the evaporator outlet is used to determine?

a. what type of thx valve is used.                                                   b. help determine the type of refrigerant in the system. 

c. assist in determining the state of the refrigerant.                 d. determine if the compressor is efficient.

 

14.  An electro-mechanical relay in a HVAC system can be used as 

 a. A solid state switching device                                                 b. a safety interlock switch                                    

 c. a SPST or DPDT switch                                                            d.  bi-metal sensor.

 

15.  A reversing valve is used in what?

a. Split system AC unit.                                                                  b. Split system heat pump.                       

c. Hydronic water heat system                                                    d. Oil steam heat system.

 

16. What happens to static pressure after changing a dirty filter.

a.

increases

b.

Static CFM changes to static FPM

c.

decreases

d.

Inclined manometer measurement must be taken to know.

17. When verifying flame rectification, the meter should be set for

a. AC volts                                  b. AC ua                                c.  DC volts                              d. DC ua        

                                        

 18. Most residential split systems work on___, while gas and oil furnaces work on_____ .

 

a. 240v,  24v,_   2404v, 24v                                                   b. 240v, 120v, 24v_   120, 24v.                                         

c.  277, 24, 120. _   120,24v.                                                 d. 277v,120v_   240v,120, 24v

 

19.  When measuring across the r and c terminals of a compressor not working, you measure 16 ohms,  across the s and c terminal, you measure 10 ohms and from r to s, 26ohms and from c to ground 16 ohms. What could be wrong?

 

a.   partially open run winding.                                               b. possible shorted start winding.              

c.  shorted common to ground.                                             d.  b and c


20.  Increasing  the  air flow across the evaporator will

a.    reduce air humidity                          b. increase air humidity                              c. have no effect                    d. decrease evaporator TD

    




 21.  When measuring natural gas at the gas valve pressure port, a pressure  reading of approximately _____ is expected.

a. 11wc                                   b. 3.5wc                                   c. 14wc                             d. 7wc

 

22.  A condensing type of gas furnace is considered

a. low efficiency type                                                              b. high efficiency type   

c. blocked vent, open draft type                                           d. Up flow type

 

23.  Higher than normal suction pressure and lower than normal high pressure can mean what?

 

a. low on refrigerant.              b. excess refrigerant.              c .defective thx valve         d . inefficient compressor.

 

24. Installing sheet metal rectangular duct runs together requires

a. UL181b mastic tape                                                             b. slip and drive cleats

c. ASHRE  approved butt joints                                               d. Square D type crimping tool

 

25.  An indoor blower motor contactor relay is typically operated at _______volts.

a. 240vlts                      b.208vlts                                  c.120vlts                          d.24vlts

 

26.  A check valve in a heat pump system is used to

a. check the refrigerant amount                                    b. allow flow in one direction only

c. reverse flow of refrigerant                                          d. work in conjunction with defrost relay

 

27. When checking PTC thermistors, your multimeter should be in the  _________ mode.

a.  volts                                 b.  milliamps                         c.  resistance                    d.  temperature   

 

28.  A current relay used for a fractional horsepower hermetic compressor has which terminals.

a.  l, 2, 5,                      b.  r, s, c ,                c.  l, m, s,            d.  1, 3, 5, 6,

 

29.  With a Delta T of 35 degrees across a warm air furnace, a btu output of 80,000, what would the necessary cfm be.

a.  211cfm                     b.  400cfm                        c. 350cfm                           d.  275cfm

 

30.  When an ac system is using a thermostatic expansion valve, the best way to check the system is to use the

a.  superheat method                                                             b.  sub cooling method  

c. pump down method                                                           d. backseat method

 

31.  Checking a parallel circuit with 30 ohms on one leg and 60 ohms on another you would expect to measure

 

a. 90 ohms,                             b.  90ma                                       c. 20 ohms                                d.  30 ohms

 

32.  CO in a gas furnace is caused by

 

a. incomplete combustion                                                             b. secondary air exposure  

c. low gas pressure                                                                        d.  too little water vapor

 

33.  One type of  electrical actuated valve used in a hot water Hydronic system is called what?

 

a.   gate valve                        b. backflow valve                            c.  zone valve                     d. check valve

 

34.  On a standard gas, 40 gallon hot water heater installation,  the vertical pipe connection to the heater should consist of

a. cut-off valve, union, drip leg, tee                                          b. cut-of f valve, 90 degree elbow, 1/2 inch black pipe nipple

c. 90 degree elbow, tee, union, check valve                         d.  in-line thermostat, union, tee,drip leg, cut-out valve

 

35.  A water circulating pump is used on what type of heating system?

 

a.    Oil Steam Furnace System                                                   b.  Gas Steam Furnace System  

c.     Hot Air HE Gas system                                                         d.  Hydronic System


36

The Montreal Protocol was intervened to deal with Global Warming________________

A.

True

 

B.

False

 

 

37

240 volts residential  AC Systems always require 3 phase power while 120vlts Systems require 1 phase________________

A.

True

 

B.

False

 

 

38

R22 was phased out of production in the year 2010________________

A.

True

 

B.

False

 

 

39

R404a is one of the replacement refrigerants for R22________________

A.

True

 

B.

False

 

 

40

VFD stands for Variable Frequency Drive________________

A.

True

 

B.

False

 

 

41

R134a  is a HCFC Refrigerant________________

A.

True

 

B.

False

 

 

42

R11 is considered a low pressure refrigerant________________

A.

True

 

B.

False

 

 

43

A Voltage type starter relay is used on fractional horse power hermetic refrigerator compressors________________

A.

True

 

B.

False

 

 

44

Ice makers go thru a harvest cycle using hot gas to assist in releasing ice from its bin.________________

A.

True

 

B.

False

 

 

45

Transformers on residential heating and cooling equipment are usually of the step-up type________________

A.

True

 

B.

False

 

 

46

The difference between a digital and an analog signal is determined by the secondary voltage of the transformer ________________

A.

True

 

B.

False

 

 

47

A higher MERV filter rating means better air filtration________________

A.

True

 

B.

False

 

 

48

Indoor air pressure should be slightly higher than outdoor pressure________________

A.

True

 

B.

False

 

 

49

HVAC capacitors because of their size are rated in farads________________

A.

True

 

B.

False

 

 

50

DC voltage is a varying voltage over time while AC voltage is at a steady state________________

A.

True

 

B.

False

 

 

 


Answers 1. b    2. b      3. c    4. a    5. c    6. b     7 .b    8. a     9. c   10. d

                  11. b  12. c  13. c  14. c  15. b  16. a  17. d  18. b  19. d  20. b

                  21. b  22. b  23. d  24. d  25 c  26. d  27. c  28. c  29. a  30. b

                  31. c  32. a  33. c  34. a  35. d  36. F  37. F  38. F  39. T  40. T

                   41. F  42. T  43. F  44. T  45. F  46. F  47. F  48. T 49. F 50. F

 

                                                    

                                                                  EPA 608 Practice Exam

 

ID

Questions

Question Image

1

When a refrigerant trace gas becomes absolutely necessary, which of the below refrigerants should be used to identify a leak?________________

A.

R-12

 

B.

R-22

 

C.

R-407C

 

D.

 R-410A

 

 

2

Heat Pumps that use R-134a should be leak checked with:________________

A.

Compressed Dry Air

 

B.

Pressurized Nitrogen

 

C.

CFC'S

 

D.

HCFC'S

 

 

3

The EPA regulations require that any appliances containing more than 50 pounds of refrigerant (except for commercial and industrial process refrigeration) must be repaired when the leak rate exceeds ______ of the charge per year.________________

A.

5%

 

B.

15%

 

C.

25%

 

D.

35%

 

 

4

Before transferring refrigerant to an empty cylinder?________________

A.

The refrigerant should be chilled.

 

B.

 The refrigerant should be mixed.

 

C.

The cylinder should be heated.

 

D.

 The cylinder should be evacuated to avoid mixing air with the recovered refrigerant.

 

 

5

Prior to replacing the condenser coil in a high pressure system, the refrigerant was recovered and stored in a refillable cylinder. The refrigerant:________________

A.

can probably be charged back into the system.

 

B.

should probably be replaced with R-410A.

 

C.

must be reclaimed.

 

D.

must be destroyed.

 

 

6

When servicing an operating unit that has a receiver/storage tank, the:________________

A.

compressor should be isolated off.

 

B.

liquid should be recovered last.

 

C.

refrigerant should be recovered into the receiver.

 

D.

gauge pressure should be achieved by venting.

 

 

7

Recovered refrigerant may contain which of the following?________________

A.

acids

 

B.

moisture

 

C.

oils

 

D.

all of the above

 

 

8

Your recovery/recycling machine has R-502 refrigerant in it. You now have to recover refrigerant from a unit with R-22. What must be done before the R-22 refrigerant can be recovered/recycled?________________

A.

nothing, as long as the recovery machine is not full

 

B.

change the expansion valve on the recovery machine

 

C.

change the filter and expansion valve on the recovery machine

 

D.

recover as much of the R-502 from the recovery unit as possible, change filter, and evacuate

 

 

9

A Recovery machine that uses a hermetic compressor will overheat when drawing a deep vacuum because:________________

A.

it runs faster than other equipment.

 

B.

the motor needs the flow of refrigerant through the compressor to provide motor cooling.

 

C.

the oils used in hermetic compressors burn at lower temperatures.

 

D.

it has a higher compression ratio limit than other equipment.

 

 

10

When using recovery or recycling equipment that was manufactured AFTER November 15, 1993: you must evacuate a system containing MORE than 200 pounds of CFC-12 to _________ before making a major repair:________________

A.

0 psig.

 

B.

4 inches of Hg vacuum.

 

C.

10 inches of Hg vacuum.

 

D.

15 inches of Hg vacuum.

 

 

11

After reaching the required recovery vacuum on a system you must:________________

A.

immediately disconnect the recycling or recovery equipment and open the system for service.

 

B.

immediately break the vacuum with nitrogen and open the system for service.

 

C.

immediately pressurize the system with nitrogen and perform a leak check.

 

D.

 wait to see if the system pressure rises, indicating that there is still refrigerant in liquid form or refrigerant trapped in the oil.

 

 

12

To change the compressor on a system containing R-410A, you must isolate the compressor then:________________

A.

Simply remove the compressor.

 

B.

Evacuate the isolated section of the system to atmospheric pressure and hold. if system pressure does not rise, remove the compressor.

 

C.

Evacuate the isolated section of the system to 10 inches of vacuum and hold. If system pressure does not rise, remove the compressor.

 

D.

Evacuate the isolated section of the system to 15 inches of vacuum and hold. If system pressure does not rise, remove the compressor.

 

 

13

A system can be evacuated to only atmospheric pressure when:________________

A.

 the repair is major.

 

B.

 the repair is followed by an evacuation of the appliance to the environment.

 

C.

leaks in the appliance make evacuation to the prescribed level unattainable.

 

D.

the appliance is being disposed.

 

 

14

Which statement is NOT true about recycling and recovery equipment manufactured after November 15, 1993?________________

A.

It must be tested by an EPA-approved third party.

 

B.

It must meet vacuum standards more stringent than those met by equipment manufactured before November 15, 1993.

 

C.

It must be equipped with low-loss fittings.

 

D.

It must have an oil separator.

 

 

15

To change the compressor on a system containing 40 pounds R-500, using a recycling machine that was manufactured AFTER November 15, 1993, you must isolate the compressor then:________________

A.

Simply remove the compressor.

 

B.

Evacuate the isolated section of the system to atmospheric pressure, then remove the compressor.

 

C.

Evacuate the isolated section of the system to 10 inches of vacuum and hold. If system pressure does not rise, remove the compressor.

 

D.

Evacuate the isolated section of the system to 15 inches of vacuum and hold. If system pressure does not rise, remove the compressor.

 

 

16

When using recovery and recycling equipment manufactured BEFORE November 15, 1993, technicians must evacuate a unit that has a normal charge of 10 pounds of CFC-500 to ___________ before disposing of the system.________________

A.

 0 psig.

 

B.

4 inches of Hg vacuum.

 

C.

10 inches of Hg vacuum.

 

D.

15 inches of Hg vacuum.

 

 

17

A deep vacuum is usually measured in:________________

A.

 psig.

 

B.

 psia.

 

C.

inches of Hg.

 

D.

microns.

 

 

18

When servicing a 60-ton packaged rooftop unit. The easiest way to check the type of refrigerant it uses is to:________________

A.

use your service gauge set and a refrigerant card.

 

B.

ask the owner.

 

C.

look at the unit name plate.

 

D.

determine the condenser size.

 

 

19

Noncondensables in a system cause a:________________

A.

lower suction pressure.

 

B.

higher suction pressure.

 

C.

lower discharge pressure.

 

D.

higher discharge pressure.

 

 

20

R-410A is different from other ASHRAE 400 series non- azeotropic blends because:________________

A.

R-410A behaves as a near azeotropic refrigerant, and can be topped off.

 

B.

R-410A is a HCFC.

 

C.

R-410A uses mineral oil.

 

D.

All of the above.

 

 

21

The evaporation temperature of R- 410A at 100 psig is about:________________

A.

0F.

 

B.

30F.

 

C.

90F.

 

D.

120F.

 

 

22

When evacuating a system, the use of a large vacuum pump could:________________

A.

cause trapped oil to freeze.

 

B.

cause trapped refrigerant to freeze.

 

C.

cause trapped water to freeze.

 

D.

causes the valves to freeze.

 

 

23

For what refrigerant(s) is an equipment room refrigerant monitor required under ASHRAE Standard 15?________________

A.

R-12

 

B.

R-134a

 

C.

R-11

 

D.

R-123

 

 

24

Every air conditioning or refrigerating system should be protected by a:________________

A.

pressure relief device.

 

B.

properly located stop valve.

 

C.

low pressure control.

 

D.

refrigerant receiver.

 

 

25

When inspecting a system for leaks, you should look for:________________

A.

frost on the pipes.

 

B.

puddles of liquid refrigerant.

 

C.

particles from the drier core.

 

D.

traces of oil.

 

 

26

On a high-pressure system _________ is an indicator of a possible leak.________________

A.

high head pressure

 

B.

low water temperature

 

C.

excessive superheat

 

D.

frequent purging

 

 

27

The EPA regulations require that leaking commercial or industrial process refrigeration equipment must be repaired when the leak rate exceeds ______ of the charge per year.________________

A.

5%

 

B.

15%

 

C.

25%

 

D.

35%

 

 

28

The fastest way to recover refrigerant from a system is to remove it in the __________ phase?________________

A.

final

 

B.

initial

 

C.

liquid

 

D.

vapor

 

 

29

The primary water source for cooling the condenser of a water-cooled recovery unit is:________________

A.

de-ionized water

 

B.

chilled water

 

C.

condenser water

 

D.

local municipal water supply

 

 

30

The recovery of refrigerant from a system as a vapor only will minimize the loss of:________________

A.

oil

 

B.

water

 

C.

refrigerant

 

D.

all of the above

 

 

31

R-410A requires a high-pressure manifold gauge and hose set. They must have a:________________

A.

2000 psig burst pressure and 400 psig working pressure.

 

B.

2000 psig burst pressure and 800 psig working pressure.

 

C.

4000 psig burst pressure and 400 psig working pressure.

 

D.

4000 psig burst pressure and 800 psig working pressure.

 

 

32

R-410A requires recovery tanks rated for at least:________________

A.

240 psig

 

B.

300 psig

 

C.

400 psig

 

D.

500 psig

 

 

33

After reaching the required recovery vacuum on a system you must:________________

A.

immediately disconnect the recycling or recovery equipment and open the system for service.

 

B.

immediately break the vacuum with nitrogen and open the system for service.

 

C.

immediately pressurize the system with nitrogen and perform a leak check.

 

D.

wait to see if the system pressure rises, indicating that there is still refrigerant in liquid form or refrigerant trapped in the oil.

 

 

34

System-dependent recovery equipment CANNOT be used when:________________

A.

the appliance is leaking.

 

B.

the compressor of the appliance is operational.

 

C.

the ambient temperature is over 115F.

 

D.

the appliance contains over 15 pounds of refrigerant.

 

 

35

Which repair would ALWAYS be considered "major" under EPA's regulations?________________

A.

replacement of an evaporator coil.

 

B.

replacement of a filter-drier.

 

C.

replacement of a schraeder valve core.

 

D.

replacement of a condenser fan motor.

 

 

36

A system can be evacuated to only atmospheric pressure when:________________

A.

the repair is major.

 

B.

the repair is followed by an evacuation of the appliance to the environment.

 

C.

leaks in the appliance make evacuation to the prescribed level unattainable.

 

D.

the appliance is being disposed.

 

 

37

When under a deep vacuum, the motor winding of a hermetic refrigeration compressor:________________

A.

will be damaged if energized.

 

B.

must be kept warm to operate properly.

 

C.

will be protected by its insulation if the compressor is started.

 

D.

will overheat only if the crankcase heater is energized.

 

 

38

The vacuum pump used to evacuate a system should be capable of pulling a vacuum of:________________

A.

10 mm Hg.

 

B.

20 mm Hg.

 

C.

500 microns.

 

D.

1000 microns.

 

 

39

The method to charge a system that has a normal charge of 80 pounds is to charge with:________________

A.

vapor through the suction line service valve.

 

B.

liquid through the discharge service valve.

 

C.

liquid through the suction service valve.

 

D.

liquid through the liquid-line service valve.

 

 

40

While R-410A is a high-pressure refrigerant, it can be stored in the back of your service van as long as:________________

A.

the temperature inside the vehicle does not exceed 125F. This is the same guidance given for R-22 and other common refrigerants.

 

B.

the temperature inside the vehicle does not exceed 125F, but R-22 can be stored in vehicles with temperatures exceeding 125F.

 

C.

the temperature inside the vehicle does not exceed 155F. This is the same guidance given for R-22 and other common refrigerants.

 

D.

the temperature inside the vehicle does not exceed 155F, but R-22 can be stored in vehicles with temperatures exceeding 155F.

 

 

41

On refrigeration units that use an open compressor; the ________________ is most likely to leak if the unit is not used for several months.________________

A.

the suction service valve

 

B.

the rotating shaft seal

 

C.

the oil drain plug

 

D.

the discharge service valve

 

 

42

When a new system has been assembled, the first thing to do is:________________

A.

evacuate the system.

 

B.

pressurize the system with an inert gas and leak check.

 

C.

pressurize the system with refrigerant to be used in the system.

 

D.

introduce an initial charge of refrigerant and start the compressor.

 

 

43

The recovery rate can be increased by:________________

A.

packing the recovery vessel in ice.

 

B.

heating the recovery vessel.

 

C.

using a smaller recovery vessel.

 

D.

using a standard vacuum pump.

 

 

44

Manifold gauge set hoses should have self-sealing connectors or hand valves to:________________

A.

minimize the chance of an explosion during use.

 

B.

prevent venting during recycling.

 

C.

prevent a vapor lock during rapid liquid transfer.

 

D.

minimize the release of refrigerant when the hoses are connected and disconnected.

 

 

45

A routine maintenance task which must be performed on refrigerant recycling machines is to _________.________________

A.

check compressor seals

 

B.

change electrical fuses

 

C.

replace moisture sight glass

 

D.

change filter and compressor oil (if any)

 

 

46

When a unit is opened for servicing, the ____________should always be replaced.________________

A.

thermostat

 

B.

metering device

 

C.

crankcase heater

 

D.

filter-drier

 

 

47

Moisture is removed from a system by:________________

A.

purging the condenser.

 

B.

draining the oil separator.

 

C.

reducing water flow to the condenser.

 

D.

using a filter drier.

 

 

48

You are going to service an older residential split system air conditioner. You would expect to find the system charged with which refrigerant?________________

A.

R-11

 

B.

R-12

 

C.

R-22

 

D.

R-502

 

 

49

Never use oxygen or compressed air to leak-check hardware because R-410A can:________________

A.

explode when mixed with air or oxygen.

 

B.

fractionate when mixed with oxygen.

 

C.

condense when exposed to oxygen.

 

D.

none of the above.

 

 

50

A charged low pressure refrigeration system can be efficiently leak checked by:________________

A.

adding compressed air, since it will be removed from the system by the Purging unit.

 

B.

operating the purge system.

 

C.

adding HCFC-22.

 

D.

raising system pressure by heating with circulated hot water or heating blankets.

 

 

  Answers   1. b  2. b  3. b  4. d  5. a  6. c  7. d 8. d  9. b 10. d  11. d  12. b  13. c  14. d 15. c

                     16. b  17. d  18.c  19. d  20. a  21. b  22. c  23. d  24. a  25. d  26. c  27. d  28. c  29. d  30. a

                     31. d  32. c  33. d  34. d  35. a  36. c  37. a  38. c  39. d  40. a  41. b  42. b  43. a  44. d  45. d

                     46. d  47. d  48. c  49. a  50. d