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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. The temperature range of the suction line from an air conditioning system should be...
Short cycling and insufficient dehumidification
The external equalizer could be plugged
The sight glass is full of liquid+the sight glass is full of gas
50-65

2. Which of the following could be the cause for a system's discharge and suction pressure being low...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A restricted metering device
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated TXV sensing bulb

3. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A bad thermostat
It is used to control refrigerant pressure in the compressor crankcase
Rise more than normal

4. 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
Current in the compressor circuit
A bad thermostat
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

5. Which of the following will cause excessive discharge pressures on an air conditioning system...
Low discharge pressure - high suction pressure - and low amp draw
High superheat and low discharge pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician B

6. Technician A says ' When charging a system using the superheat method - adding refrigerant to the system will increase the superheat.' Technician B says 'When charging a system using the superheat method - adding refrigerant will decrease the superhe
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Flooding the condenser - cycling condenser fans - and dampering condenser air

7. 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
Technician A is correct
Technician A
An uninsulated suction line and a restricted metering device
3 psig

8. The best description of a relay would be...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Contains a solenoid coil and one or more sets of contacts
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

9. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An increase of air leakage from ductwork
The sight glass is full of liquid+the sight glass is full of gas
An undercharge and low ambient conditions
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

10. What are two common symptoms of a rooftop air conditioning system that operates with a reverse-acting high-pressure control stuck in the closed position...
A low refrigerant charge
A restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B

11. 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
Short cycling and insufficient dehumidification
An open internal overload protector
Technician B
An undercharge and low ambient conditions

12. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
An open internal overload protector
Evaporator and compressor
Bad compressor valve
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

13. Which of the following could be the cause for a system's discharge and suction pressure being low...
An increase in low-side pressure
Short cycling and insufficient dehumidification
A restricted metering device
An uninsulated suction line and a restricted metering device

14. 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
Technician A is correct
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
A vacuum test+oil traces around fittings+soap bubble solution

15. A commercial customer calls on a 90
50-65
The system has been overcharged+The system has air trapped in the condenser
The sensing bulb at a lower temperature than the valve body
Both technicians are incorrect

16. 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
Technician A
A plugged filter drier
A dirty condenser - recirculation of condenser air - and a defective condenser fan
('Y' and 'C') and ('G' and 'C')

17. 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
A vacuum test+oil traces around fittings+soap bubble solution
An open internal overload protector
Increases starting torque
The sight glass is full of liquid+the sight glass is full of gas

18. Superheat is found in an air conditioning system in the...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Evaporator and compressor
Technician B
High superheat and low discharge pressure

19. A customer calls with an insufficient cooling complaint on a 90
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Evaporator and compressor
Current in the compressor circuit

20. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small
Condenser fans operating during a low ambient condition and a low suction pressure

21. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
The internal overload is opened
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
It keeps a constant superheat in the evaporator

22. When troubleshooting a split-system air conditioner - it is found that the compressor motor is humming but not starting. Technician A says that it could be an open internal overload protector. Technician B says that it could be a blown fuse. Which te
A low refrigerant charge
The discharge pressure increases and the amperage increases
Run with high head and high suction pressure
Both technicians are incorrect

23. What type of problems can be caused by an oversized air conditioning system...
An increase of air leakage from ductwork
Short cycling and insufficient dehumidification
Bad compressor valve
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

24. 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
Broken rings+broken valves+seized bearings
Low discharge pressure - high suction pressure - and low amp draw
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Rise more than normal

25. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Current in the compressor circuit
The sight glass is full of liquid+the sight glass is full of gas
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
('Y' and 'C') and ('G' and 'C')

26. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The superheat increases and the subcooling decreases
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

27. A commercial customer calls complaining that her rooftop air conditioning system is not operating. The technician arrives on the job and sets the thermostat to cooling - then notices that the indoor fan is not operating. The technician then sets the

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28. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
110-120
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Run with high head and high suction pressure
An uninsulated TXV sensing bulb

29. A commercial customer calls complaining that her rooftop air conditioning system is not operating. The technician arrives on the job and sets the thermostat to cooling - then notices that the indoor fan is not operating. The technician then sets the

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30. A technician receives an air conditioning service call stating that the system is operating but isn't cooling properly. When the technician arrives - she notices that the compressor has recently been changed and it is an are-22 system. She checks the
The sight glass is full of liquid+the sight glass is full of gas
Technician B
An increase of air leakage from ductwork
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

31. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Technician B
The external equalizer could be plugged

32. A restricted air filter in an air conditioning system can be identified by...
('Y' and 'C') and ('G' and 'C')
Low superheat
Evaporator and compressor
The sight glass is full of liquid+the sight glass is full of gas

33. Which of the following is a common cause of an excessively low superheat on a TXV system...
An increase of air leakage from ductwork
An undercharged system+insufficient airflow over the evaporator coil
Partially frosted evaporator and high superheat
A sensing bulb improperly connected to the suction line

34. 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
The oil pump pressure and the crankcase pressure
The sensing bulb at a lower temperature than the valve body
Broken rings+broken valves+seized bearings

35. What is the purpose of a CPR valve...
A start relay
Technician B
Always have some liquid present in the bulb and diaphragm
It is used to control refrigerant pressure in the compressor crankcase

36. What type of problems can be caused by an oversized air conditioning system...
Rise more than normal
Short cycling and insufficient dehumidification
It is used to control refrigerant pressure in the compressor crankcase
It keeps a constant superheat in the evaporator

37. A liquid-charged TXV bulb will...
The superheat will increase and the low-side pressure will decrease
('Y' and 'C') and ('G' and 'C')
Always have some liquid present in the bulb and diaphragm
Technician B

38. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
The system has been overcharged+The system has air trapped in the condenser
Current in the compressor circuit
An uninsulated suction line and a restricted metering device

39. What are the operating pressures of an oil pressure safety switch...
A sensing bulb improperly connected to the suction line
Condenser fans operating during a low ambient condition and a low suction pressure
Run with high head and high suction pressure
The oil pump pressure and the crankcase pressure

40. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A low refrigerant charge
The system has been overcharged+The system has air trapped in the condenser
The superheat will increase and the low-side pressure will decrease
A blown fuse

41. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The oil pump pressure and the crankcase pressure
3 psig
110-120

42. 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
Technician B
It is used to control refrigerant pressure in the compressor crankcase
Evaporator and compressor
A sensing bulb improperly connected to the suction line

43. 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
Run with high head and high suction pressure
The oil pump pressure and the crankcase pressure
Technician A is correct
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

44. Air filters should be replaced...
Whenever necessary
A start relay
The discharge pressure increases and the amperage increases
Technician B

45. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The external equalizer could be plugged
A blown fuse
Broken rings+broken valves+seized bearings
The superheat will increase and the low-side pressure will decrease

46. What is the purpose of an EPR valve...
An increase of air leakage from ductwork
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

47. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
50-65
Clean the condenser coil

48. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An open internal overload protector
Technician B

49. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A defective circuit breaker
A blown fuse
Low discharge pressure - high suction pressure - and low amp draw
A missing air filter+improper rotation of the indoor blower+blower too small

50. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Low discharge pressure - high suction pressure - and low amp draw
The discharge pressure increases and the amperage increases
Technician B