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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. 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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2. A compressor having tight bearings would cause the current value to...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A plugged filter drier
A start relay
Rise more than normal

3. 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...
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

4. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Low voltage and a faulty start relay
High superheat and low discharge pressure
Lack of airflow
20 to 30

5. 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
3 psig
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Broken rings+broken valves+seized bearings

6. 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
High superheat and low discharge pressure
A sensing bulb improperly connected to the suction line
Technician A
Technician B

7. What is the purpose of the TXV...
It would cause the low-side pressure to decrease
It keeps a constant superheat in the evaporator
Dirty condenser - bent condenser fins - and air recirculating over the condenser
20 to 30

8. What causes the automatic expansion valve to close...
Both technicians are incorrect
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase in low-side pressure

9. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Contains a solenoid coil and one or more sets of contacts
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The superheat will increase and the low-side pressure will decrease
Rise more than normal

10. 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
A start capacitor and a solid-state relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

11. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Clean the condenser coil
Evaporator and compressor
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Current in the compressor circuit

12. Why is it unsafe to operate an air conditioning system with a low charge...
It is used to control refrigerant pressure in the compressor crankcase
Low voltage and a faulty start relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are correct

13. The internal overload of an air conditioning compressor senses winding temperature and...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An uninsulated TXV sensing bulb
Whenever necessary
Current in the compressor circuit

14. 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 low refrigerant charge
Technician B
An overcharged system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

15. What are three methods for controlling a system's high-side pressure during low ambient conditions...
It is used to control refrigerant pressure in the compressor crankcase
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air
20 to 30

16. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
A vacuum test+oil traces around fittings+soap bubble solution
Always have some liquid present in the bulb and diaphragm
Clean the condenser coil

17. What type of problems can be caused by an oversized air conditioning system...
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A sensing bulb improperly connected to the suction line
Short cycling and insufficient dehumidification

18. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Condenser fans operating during a low ambient condition and a low suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
3 psig

19. Which of the following is a common cause of an excessively low superheat on a TXV system...
A start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
('Y' and 'C') and ('G' and 'C')
A sensing bulb improperly connected to the suction line

20. 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 undercharge and low ambient conditions
Both technicians are incorrect
The low-side pressure will decrease and the evaporator coil will be partially frosted
An open internal overload protector

21. Which of the following could be the cause for a system's discharge and suction pressure being low...
3 psig
The system has been overcharged+The system has air trapped in the condenser
It would cause the low-side pressure to decrease
A restricted metering device

22. A system that is operating with a clear sight glass shows...
Bad compressor valve
The sight glass is full of liquid+the sight glass is full of gas
An open internal overload protector
A sensing bulb improperly connected to the suction line

23. A hard-start kit for an air conditioning system...
Partially frosted evaporator and high superheat
The sight glass is full of liquid+the sight glass is full of gas
'G' to 'C'
Increases starting torque

24. A 220-volt 30-amp motor circuit keeps tripping the breaker after the motor is started. The starting amperage is 60 amps. When measuring the amperage of the circuit - This is drawn for a brief moment. After startup - the amperage drops to 22 amps and
The system has been overcharged+The system has air trapped in the condenser
A defective circuit breaker
The sight glass is full of liquid+the sight glass is full of gas
The discharge pressure increases and the amperage increases

25. A system that is operating with a clear sight glass shows...
Broken rings+broken valves+seized bearings
Technician B
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas

26. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Rise more than normal
Technician B
The internal overload is opened
A missing air filter+improper rotation of the indoor blower+blower too small

27. What component is most often the cause of a start capacitor failure...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start relay
A blown fuse
A sensing bulb improperly connected to the suction line

28. 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...
It would cause the low-side pressure to decrease
The superheat will increase and the low-side pressure will decrease
('Y' and 'C') and ('G' and 'C')
Low voltage and a faulty start relay

29. Which of the following can cause excessive subcooling...
An overcharged system
Technician B
An undercharged system+insufficient airflow over the evaporator coil
Technician B

30. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The internal overload is opened
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A plugged filter drier

31. The technician observes that the compressor is not operating. The compressor windings read 5 ohms start to run - run to common is opened - and start to common is opened. The technician concludes that...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The internal overload is opened
Technician A

32. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
A blown fuse
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated suction line and a restricted metering device

33. 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')
The sight glass is full of liquid+the sight glass is full of gas
Technician B
The superheat increases and the subcooling decreases

34. The best description of a relay would be...
It would cause the low-side pressure to decrease
Contains a solenoid coil and one or more sets of contacts
Evaporator and compressor
Technician A

35. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Technician B
An uninsulated suction line and a restricted metering device
Low superheat
Contains a solenoid coil and one or more sets of contacts

36. Which of the following is a possible cause for a compressor to overheat...
The oil pump pressure and the crankcase pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A low refrigerant charge
A vacuum test+oil traces around fittings+soap bubble solution

37. 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
Short cycling and insufficient dehumidification
Both technicians are incorrect
('Y' and 'C') and ('G' and 'C')
The superheat increases and the subcooling decreases

38. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
An uninsulated TXV sensing bulb
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
An acid-core suction line drier

39. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat increases and the subcooling decreases
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

40. A customer calls with an insufficient cooling complaint on a 90
Current in the compressor circuit
50-65
Both technicians are incorrect
Technician B

41. The internal overload of an air conditioning compressor senses winding temperature and...
An increase in suction pressure and an increase in discharge pressure
Current in the compressor circuit
The low-side pressure will decrease and the evaporator coil will be partially frosted
It keeps a constant superheat in the evaporator

42. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
50-65
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
110-120

43. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The internal overload is opened
'G' to 'C'
Contains a solenoid coil and one or more sets of contacts
An undercharge and low ambient conditions

44. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Both technicians are incorrect
A start capacitor and a solid-state relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

45. What is the purpose of an EPR valve...
50-65
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Increases starting torque
A bad thermostat

46. What three things can prevent an air conditioning system from releasing heat at the proper rate...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Clean the condenser coil
('Y' and 'C') and ('G' and 'C')
A dirty condenser - recirculation of condenser air - and a defective condenser fan

47. 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 dirty condenser - recirculation of condenser air - and a defective condenser fan
Condenser fans operating during a low ambient condition and a low suction pressure
Short cycling and insufficient dehumidification
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

48. What is the purpose of a CPR valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It is used to control refrigerant pressure in the compressor crankcase
Current in the compressor circuit
A dirty condenser - recirculation of condenser air - and a defective condenser fan

49. 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 internal overload is opened
Contains a solenoid coil and one or more sets of contacts
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

50. A customer calls with an insufficient cooling complaint on a 90
It would cause the low-side pressure to decrease
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
20 to 30