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NATE Air Conditioning Troubleshooting

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. A restricted air filter in an air conditioning system can be identified by...
It would cause the low-side pressure to decrease
Low superheat
Bad compressor valve
The internal overload is opened

2. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An increase in low-side pressure
Short cycling and insufficient dehumidification
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Whenever necessary

3. What is the purpose of an EPR valve...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
The external equalizer could be plugged
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

4. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the system is using are-22 with the high-side pressure at 290 psig and the low-side pressure at 85 psig. The ambient temperature is 85
The sight glass is full of liquid+the sight glass is full of gas
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician A
Technician B

5. A compressor motor starts and operates for a short period of time and cycles on the external overload protector. What are two possible problems that could cause this...
An increase in low-side pressure
Low voltage and a faulty start relay
Contains a solenoid coil and one or more sets of contacts
Dirty condenser - bent condenser fins - and air recirculating over the condenser

6. A customer who owns a split air conditioning system complains that his system has been running but his house doesn't seem to be cooling properly. When the service technician arrives on the job - he or she finds that the indoor blower is operating and
Clean the condenser coil
A missing air filter+improper rotation of the indoor blower+blower too small
Low superheat
The superheat increases and the subcooling decreases

7. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A start capacitor and a solid-state relay
Contains a solenoid coil and one or more sets of contacts

8. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
The oil pump pressure and the crankcase pressure
Bad compressor valve
Technician B

9. An air conditioning system that uses a fan center has an inoperable indoor blower. When the thermostat is set for cooling and dialed below room temperature - a test with the voltmeter shows that there is 24 volts across terminals 'are' and 'G' at the
Low voltage and a faulty start relay
A bad thermostat
The system has been overcharged+The system has air trapped in the condenser
The superheat will increase and the low-side pressure will decrease

10. A system that is being serviced has been evacuated down to 500 microns. When the gauges are closed and the vacuum pump is turned off - the pressure starts to increase and stops at 1000 microns. Technician A says that the system has a leak and needs t
Partially frosted evaporator and high superheat
Technician B
50-65
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

11. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
It is used to control refrigerant pressure in the compressor crankcase
An increase in low-side pressure
Run with high head and high suction pressure

12. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Condenser fans operating during a low ambient condition and a low suction pressure
High suction pressure and low superheat
Rise more than normal

13. What problem or problems can cause low discharge and suction pressure...
Technician B
The system has been overcharged+The system has air trapped in the condenser
An undercharged system+insufficient airflow over the evaporator coil
Current in the compressor circuit

14. A hard-start kit consists of...
A start capacitor and a solid-state relay
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
'G' to 'C'
Both technicians are correct

15. A customer calls with an insufficient cooling complaint on a 90
The sight glass is full of liquid+the sight glass is full of gas
An undercharge and low ambient conditions
Technician B
High suction pressure and low superheat

16. What are the operating pressures of an oil pressure safety switch...
3 psig
Technician B
A plugged filter drier
The oil pump pressure and the crankcase pressure

17. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician A is correct
A missing air filter+improper rotation of the indoor blower+blower too small
Both technicians are incorrect

18. Which of the following can cause excessive subcooling...
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged
An overcharged system

19. A customer calls to complain that his central air conditioning system is not cooling properly. The technician arrives on the job. He or she notices that the indoor blower has adequate airflow and the outdoor condenser fan is operating - but the compr
An open internal overload protector
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas

20. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
A start relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A start capacitor and a solid-state relay

21. A restricted air filter in an air conditioning system can be identified by...
The sight glass is full of liquid+the sight glass is full of gas
Low superheat
An uninsulated suction line and a restricted metering device
Contains a solenoid coil and one or more sets of contacts

22. Which of the following can cause excessive subcooling...
Both technicians are correct
Both technicians are incorrect
An uninsulated TXV sensing bulb
An overcharged system

23. An air conditioning system that uses a fan center has an inoperable indoor blower. When the thermostat is set for cooling and dialed below room temperature - a test with the voltmeter shows that there is 24 volts across terminals 'are' and 'G' at the
The superheat will increase and the low-side pressure will decrease
Low superheat
A bad thermostat
A restricted metering device

24. Technician A says that to manually pump down an air conditioning system with a two-position service valve - the liquid line must be front-seated and the high- and low-side pressure will decrease to 0 psig when the pump-down is complete. Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It would cause the low-side pressure to decrease
The system has been overcharged+The system has air trapped in the condenser
Technician A is correct

25. A system that is operating with a clear sight glass shows...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated suction line and a restricted metering device

26. A party-store owner tried to adjust the water valve on his water-cooled condensing unit - then he called for assistance from an HVAC/are service technician. It was found that when servicing the unit - the outlet water temperature was too low. Technic
It keeps a constant superheat in the evaporator
Technician B
The oil pump pressure and the crankcase pressure
An uninsulated suction line and a restricted metering device

27. What component is most often the cause of a start capacitor failure...
An overcharged system
A start relay
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

28. Which of the following is a common cause of an excessively low superheat on a TXV system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
High superheat and low discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A sensing bulb improperly connected to the suction line

29. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Rise more than normal
A vacuum test+oil traces around fittings+soap bubble solution
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

30. A customer who owns a split air conditioning system complains that his system has been running but his house doesn't seem to be cooling properly. When the service technician arrives on the job - he or she finds that the indoor blower is operating and
An undercharge and low ambient conditions
Current in the compressor circuit
An overcharged system
Clean the condenser coil

31. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An undercharged system+insufficient airflow over the evaporator coil
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
High suction pressure and low superheat
The superheat increases and the subcooling decreases

32. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A blown fuse
An uninsulated TXV sensing bulb
A plugged filter drier
An overcharged system

33. A hard-start kit for an air conditioning system...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
High suction pressure and low superheat
Increases starting torque
The system has been overcharged+The system has air trapped in the condenser

34. Why is it unsafe to operate an air conditioning system with a low charge...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Lack of airflow
Both technicians are correct

35. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Run with high head and high suction pressure
A plugged filter drier
20 to 30
Low superheat

36. A technician arrives on the job and the customer complains that there is no cooling on his rooftop unit. Troubleshooting the system - the technician finds that the compressor is faulty. He notices that there is another faulty compressor laying next t
It is used to control refrigerant pressure in the compressor crankcase
Broken rings+broken valves+seized bearings
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

37. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
110-120
An undercharge and low ambient conditions
20 to 30

38. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Both technicians are incorrect
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated TXV sensing bulb
The oil pump pressure and the crankcase pressure

39. What causes the automatic expansion valve to close...
Technician A
An increase in low-side pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
50-65

40. Which of the following can cause low superheat in a TXV system...
The internal overload is opened
Technician B
An uninsulated TXV sensing bulb
Technician B

41. Which of the following is a possible cause for a compressor to overheat...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B
Partially frosted evaporator and high superheat
A low refrigerant charge

42. What are three methods for controlling a system's high-side pressure during low ambient conditions...
It would cause the low-side pressure to decrease
The external equalizer could be plugged
Contains a solenoid coil and one or more sets of contacts
Flooding the condenser - cycling condenser fans - and dampering condenser air

43. A split-system air conditioner that uses a piston-type metering device is to be charged with are-22. Technician A says that the outdoor dry-bulb temperature is needed to determine the proper superheat. Technician B says that the indoor wet-bulb tempe
Both technicians are correct
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

44. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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45. Which of the following is a possible cause for a compressor to overheat...
A defective circuit breaker
A low refrigerant charge
Both technicians are correct
The sensing bulb at a lower temperature than the valve body

46. A customer calls and complains that his air conditioning system is not operating properly. It is noticed that the compressor is not operating. A check on the run capacitor shows that there is 33 uf and the rating on the capacitor is 40 uf. Technician
A restricted metering device
Technician B
The discharge pressure increases and the amperage increases
Partially frosted evaporator and high superheat

47. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
An overcharged system
Flooding the condenser - cycling condenser fans - and dampering condenser air
The discharge pressure increases and the amperage increases

48. Which of the following could be the cause for a system's discharge and suction pressure being low...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An overcharged system
The system has been overcharged+The system has air trapped in the condenser
A restricted metering device

49. What problem or problems can cause low discharge and suction pressure...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It is used to control refrigerant pressure in the compressor crankcase
An undercharged system+insufficient airflow over the evaporator coil
A blown fuse

50. Technician A says that if you connect 208 volts to the primary side of a 240-volt/ 24-volt transformer - the transformer will burn out. Technician B says that if you connect 208 volts to the primary side of a 240-volt/24-volt transformer - the contro
('Y' and 'C') and ('G' and 'C')
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure