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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. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
('Y' and 'C') and ('G' and 'C')
Both technicians are correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

2. A system that uses a thermal electric expansion valve...
An undercharge and low ambient conditions
('Y' and 'C') and ('G' and 'C')
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

3. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Short cycling and insufficient dehumidification
Broken rings+broken valves+seized bearings

4. What are two common symptoms of refrigerant leaks in an air conditioning system...
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Partially frosted evaporator and high superheat

5. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in suction pressure and an increase in discharge pressure

6. 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
The superheat will increase and the low-side pressure will decrease
Current in the compressor circuit
('Y' and 'C') and ('G' and 'C')

7. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The discharge pressure increases and the amperage increases
A vacuum test+oil traces around fittings+soap bubble solution
The external equalizer could be plugged

8. 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
Contains a solenoid coil and one or more sets of contacts
Evaporator and compressor
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B

9. If a rooftop air conditioning system does not have any means of low ambient protection - what will be two symptoms of the system when operating under a low ambient condition...
A missing air filter+improper rotation of the indoor blower+blower too small
High superheat and low discharge pressure
Run with high head and high suction pressure
Technician B

10. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Technician B
Low voltage and a faulty start relay
A defective circuit breaker

11. What three things can prevent an air conditioning system from releasing heat at the proper rate...
'G' to 'C'
'G' to 'C'
Technician A
A dirty condenser - recirculation of condenser air - and a defective condenser fan

12. 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
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The internal overload is opened

13. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A vacuum test+oil traces around fittings+soap bubble solution
Whenever necessary
The system has been overcharged+The system has air trapped in the condenser
A missing air filter+improper rotation of the indoor blower+blower too small

14. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Both technicians are correct
The superheat increases and the subcooling decreases
Technician B
An acid-core suction line drier

15. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Increases starting torque
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An undercharged system+insufficient airflow over the evaporator coil

16. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The sensing bulb at a lower temperature than the valve body
Technician B

17. 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...
Low voltage and a faulty start relay
A low refrigerant charge
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A restricted metering device

18. 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
A bad thermostat
A start capacitor and a solid-state relay
Run with high head and high suction pressure
A defective circuit breaker

19. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
A start relay
It keeps a constant superheat in the evaporator
An undercharged system+insufficient airflow over the evaporator coil

20. What problem or problems can cause low discharge and suction pressure...
An uninsulated suction line and a restricted metering device
An undercharged system+insufficient airflow over the evaporator coil
A restricted metering device
The discharge pressure increases and the amperage increases

21. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Increases starting torque
It would cause the low-side pressure to decrease
A restricted metering device

22. The temperature range of the suction line from an air conditioning system should be...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
50-65
An uninsulated suction line and a restricted metering device
Technician A

23. A restricted air filter in an air conditioning system can be identified by...
Bad compressor valve
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A
Low superheat

24. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
Technician B
A bad thermostat
The discharge pressure increases and the amperage increases
An increase of air leakage from ductwork

25. The temperature range of the suction line from an air conditioning system should be...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A start capacitor and a solid-state relay
50-65
Technician B

26. Which of the following will cause excessive discharge pressures on an air conditioning system...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
50-65
An overcharged system

27. Superheat is found in an air conditioning system in the...
Evaporator and compressor
Clean the condenser coil
A plugged filter drier
The discharge pressure increases and the amperage increases

28. Which of the following is a possible cause for a compressor to overheat...
High superheat and low discharge pressure
Rise more than normal
Rise more than normal
A low refrigerant charge

29. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Technician B
Increases starting torque
An open internal overload protector

30. A hard-start kit consists of...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A start capacitor and a solid-state relay
The internal overload is opened
Low voltage and a faulty start relay

31. A hard-start kit for an air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

32. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the outdoor condensing unit is operating - but the indoor blower is not in operation. Technician A says that it is possible that it is a bad fu
An uninsulated suction line and a restricted metering device
Both technicians are incorrect
Current in the compressor circuit
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

33. Why is it unsafe to operate an air conditioning system with a low charge...
A defective circuit breaker
A restricted metering device
The oil pump pressure and the crankcase pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

34. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air
('Y' and 'C') and ('G' and 'C')
Run with high head and high suction pressure

35. What is the purpose of an EPR valve...
Bad compressor valve
It would cause the low-side pressure to decrease
It is used to control refrigerant pressure in the compressor crankcase
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

36. 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
Technician B
20 to 30
Current in the compressor circuit

37. What are the symptoms of an air conditioning system that has a low charge...
Low discharge pressure - high suction pressure - and low amp draw
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The low-side pressure will decrease and the evaporator coil will be partially frosted
The sight glass is full of liquid+the sight glass is full of gas

38. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
Technician B
It would cause the low-side pressure to decrease
An overcharged system

39. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
A start capacitor and a solid-state relay

40. If 24 volts are present to the contactor coil on an air conditioning system and the condenser fan or compressor is inoperative - which of the following could be at fault...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Flooding the condenser - cycling condenser fans - and dampering condenser air
A blown fuse

41. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Rise more than normal
The superheat will increase and the low-side pressure will decrease
A bad thermostat

42. What is the purpose of the TXV...
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are correct
Rise more than normal
It keeps a constant superheat in the evaporator

43. A customer calls and complains that her high-efficiency air conditioning system is operating - but is not cooling properly. Further investigation shows that the system is using a TXV type of metering device. A subcooling check shows that the system a
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The external equalizer could be plugged
('Y' and 'C') and ('G' and 'C')

44. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged
Low superheat

45. When using a vapor-charged TXV bulb - it is necessary to have...
Clean the condenser coil
The sight glass is full of liquid+the sight glass is full of gas
The sensing bulb at a lower temperature than the valve body
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

46. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Low discharge pressure - high suction pressure - and low amp draw
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A vacuum test+oil traces around fittings+soap bubble solution

47. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Condenser fans operating during a low ambient condition and a low suction pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Run with high head and high suction pressure
Both technicians are incorrect

48. 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
Technician B
Partially frosted evaporator and high superheat
Increases starting torque
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

49. What are common methods that are used for leak-testing a system...
High suction pressure and low superheat
A blown fuse
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque

50. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Lack of airflow
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B