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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. What causes the automatic expansion valve to close...
Whenever necessary
Bad compressor valve
An increase in low-side pressure
Partially frosted evaporator and high superheat

2. 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
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
An open internal overload protector
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

3. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Current in the compressor circuit
A defective circuit breaker
Technician A
An acid-core suction line drier

4. What is the purpose of a CPR valve...
Rise more than normal
It is used to control refrigerant pressure in the compressor crankcase
An open internal overload protector
An uninsulated TXV sensing bulb

5. Air filters should be replaced...
50-65
Technician B
Whenever necessary
Evaporator and compressor

6. A system that is operating with a clear sight glass shows...
Whenever necessary
The sight glass is full of liquid+the sight glass is full of gas
It would cause the low-side pressure to decrease
Partially frosted evaporator and high superheat

7. Superheat is found in an air conditioning system in the...
('Y' and 'C') and ('G' and 'C')
A start relay
Evaporator and compressor
The superheat will increase and the low-side pressure will decrease

8. 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...
High superheat and low discharge pressure
A bad thermostat
A vacuum test+oil traces around fittings+soap bubble solution
An uninsulated suction line and a restricted metering device

9. 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
Run with high head and high suction pressure
Broken rings+broken valves+seized bearings
A dirty condenser - recirculation of condenser air - and a defective condenser fan
50-65

10. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
50-65
Condenser fans operating during a low ambient condition and a low suction pressure
Evaporator and compressor
20 to 30

11. 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
Technician B
High superheat and low discharge pressure
Technician A is correct
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

12. A compressor having tight bearings would cause the current value to...
Low voltage and a faulty start relay
Technician A is correct
Rise more than normal
Both technicians are incorrect

13. 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
An increase of air leakage from ductwork
The internal overload is opened

14. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
An increase in low-side pressure
An undercharged system+insufficient airflow over the evaporator coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
A missing air filter+improper rotation of the indoor blower+blower too small

15. A hard-start kit consists of...
High suction pressure and low superheat
The internal overload is opened
Run with high head and high suction pressure
A start capacitor and a solid-state relay

16. 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...
Technician B
Low superheat
Current in the compressor circuit
The internal overload is opened

17. 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
'G' to 'C'
An increase in suction pressure and an increase in discharge pressure
Broken rings+broken valves+seized bearings

18. Which of the following can cause low superheat in a TXV system...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Contains a solenoid coil and one or more sets of contacts
An uninsulated TXV sensing bulb

19. A restricted air filter in an air conditioning system can be identified by...
Both technicians are correct
The oil pump pressure and the crankcase pressure
Low superheat
Whenever necessary

20. Which of the following is a common cause of an excessively low superheat on a TXV system...
Low discharge pressure - high suction pressure - and low amp draw
A sensing bulb improperly connected to the suction line
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

21. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
An acid-core suction line drier
Bad compressor valve
Technician B
Technician B

22. Which of the following can cause low superheat in a TXV system...
Broken rings+broken valves+seized bearings
110-120
An uninsulated TXV sensing bulb
Low voltage and a faulty start relay

23. 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
An increase in low-side pressure
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 B

24. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Run with high head and high suction pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B

25. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
110-120
High superheat and low discharge pressure
Technician A is correct

26. What are common methods that are used for leak-testing a system...
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A vacuum test+oil traces around fittings+soap bubble solution
Technician A

27. 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
Technician B
An undercharge and low ambient conditions
The system has been overcharged+The system has air trapped in the condenser
Both technicians are correct

28. Insufficient airflow can be caused by...
An increase in suction pressure and an increase in discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An increase of air leakage from ductwork

29. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
The discharge pressure increases and the amperage increases
20 to 30

30. A customer calls with an insufficient cooling complaint on a 90
An undercharge and low ambient conditions
Always have some liquid present in the bulb and diaphragm
The external equalizer could be plugged
Technician B

31. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
An increase in low-side pressure
Technician A is correct
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

32. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
It would cause the low-side pressure to decrease
Rise more than normal
Low voltage and a faulty start relay

33. 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...

34. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An uninsulated suction line and a restricted metering device
3 psig
'G' to 'C'
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

35. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Clean the condenser coil
Clean the condenser coil
Low voltage and a faulty start relay
Dirty condenser - bent condenser fins - and air recirculating over the condenser

36. 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 system has been overcharged+The system has air trapped in the condenser
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low voltage and a faulty start relay

37. 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
Clean the condenser coil
Technician B
Both technicians are incorrect
A start relay

38. What are two common symptoms of refrigerant leaks in an air conditioning system...
The superheat will increase and the low-side pressure will decrease
Always have some liquid present in the bulb and diaphragm
Partially frosted evaporator and high superheat
An overcharged system

39. 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...
50-65
Both technicians are correct
Low voltage and a faulty start relay
Condenser fans operating during a low ambient condition and a low suction pressure

40. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
An open internal overload protector
Lack of airflow
Bad compressor valve
Run with high head and high suction pressure

41. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The discharge pressure increases and the amperage increases
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low discharge pressure - high suction pressure - and low amp draw

42. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Both technicians are incorrect
An undercharge and low ambient conditions
An uninsulated suction line and a restricted metering device
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

43. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil
Evaporator and compressor

44. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A plugged filter drier
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
It is used to control refrigerant pressure in the compressor crankcase
An undercharge and low ambient conditions

45. The temperature range of the suction line from an air conditioning system should be...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
50-65
Run with high head and high suction pressure
Condenser fans operating during a low ambient condition and a low suction pressure

46. Superheat is found in an air conditioning system in the...
Evaporator and compressor
A sensing bulb improperly connected to the suction line
Clean the condenser coil
Both technicians are correct

47. What is the purpose of a CPR valve...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
It is used to control refrigerant pressure in the compressor crankcase
('Y' and 'C') and ('G' and 'C')
20 to 30

48. The best description of a relay would be...
Always have some liquid present in the bulb and diaphragm
The external equalizer could be plugged
Contains a solenoid coil and one or more sets of contacts
A vacuum test+oil traces around fittings+soap bubble solution

49. Which of the following is a common cause of an excessively low superheat on a TXV system...
Partially frosted evaporator and high superheat
A sensing bulb improperly connected to the suction line
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat increases and the subcooling decreases

50. 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...
('Y' and 'C') and ('G' and 'C')
An uninsulated TXV sensing bulb
The oil pump pressure and the crankcase pressure
Low voltage and a faulty start relay