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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. 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
Both technicians are incorrect
High suction pressure and low superheat
High suction pressure and low superheat

2. Which of the following could be the cause for a system's discharge and suction pressure being low...
Technician B
A restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A low refrigerant charge

3. 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
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An open internal overload protector

4. A commercial customer calls on a 90
Lack of airflow
Whenever necessary
The system has been overcharged+The system has air trapped in the condenser
Technician B

5. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
The system has been overcharged+The system has air trapped in the condenser
A start capacitor and a solid-state relay
Flooding the condenser - cycling condenser fans - and dampering condenser air

6. 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
The internal overload is opened
Both technicians are correct
The superheat increases and the subcooling decreases

7. 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...
A blown fuse
The oil pump pressure and the crankcase pressure
A start relay
Both technicians are incorrect

8. 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...
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated suction line and a restricted metering device
Low voltage and a faulty start relay
Broken rings+broken valves+seized bearings

9. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
The discharge pressure increases and the amperage increases
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

10. 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
The oil pump pressure and the crankcase pressure
An open internal overload protector
A defective circuit breaker
Technician A is correct

11. Insufficient airflow can be caused by...
Partially frosted evaporator and high superheat
'G' to 'C'
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase of air leakage from ductwork

12. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician A is correct
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Run with high head and high suction pressure

13. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
A restricted metering device
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A missing air filter+improper rotation of the indoor blower+blower too small

14. A customer calls with an insufficient cooling complaint on a 90
Technician B
'G' to 'C'
An acid-core suction line drier
A low refrigerant charge

15. A customer calls with an insufficient cooling complaint on a 90
Clean the condenser coil
Technician B
3 psig
Broken rings+broken valves+seized bearings

16. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
3 psig
Technician B
110-120
Partially frosted evaporator and high superheat

17. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The external equalizer could be plugged
A blown fuse
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat increases and the subcooling decreases

18. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
It is used to control refrigerant pressure in the compressor crankcase
The sensing bulb at a lower temperature than the valve body
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

19. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Both technicians are correct
The superheat will increase and the low-side pressure will decrease
A restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser

20. 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
Both technicians are incorrect
Clean the condenser coil
The oil pump pressure and the crankcase pressure
('Y' and 'C') and ('G' and 'C')

21. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An overcharged system
20 to 30
A start relay
Clean the condenser coil

22. Which of the following is a possible cause for a compressor to overheat...
Low superheat
An overcharged system
Technician B
A low refrigerant charge

23. What is the purpose of an EPR valve...
High superheat and low discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A sensing bulb improperly connected to the suction line
Both technicians are incorrect

24. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Technician B
An overcharged system
Both technicians are correct

25. 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
The oil pump pressure and the crankcase pressure
A start relay

26. Which of the following can cause excessive subcooling...
High superheat and low discharge pressure
Low superheat
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An overcharged system

27. A liquid-charged TXV bulb will...
A low refrigerant charge
Both technicians are incorrect
Current in the compressor circuit
Always have some liquid present in the bulb and diaphragm

28. 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 start capacitor and a solid-state relay
Both technicians are incorrect
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The discharge pressure increases and the amperage increases

29. 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
Whenever necessary
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

30. 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
A defective circuit breaker
Condenser fans operating during a low ambient condition and a low suction pressure
'G' to 'C'
Rise more than normal

31. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve

32. Which of the following can cause low superheat in a TXV system...
Partially frosted evaporator and high superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated TXV sensing bulb

33. What are common methods that are used for leak-testing a system...
('Y' and 'C') and ('G' and 'C')
A start capacitor and a solid-state relay
A vacuum test+oil traces around fittings+soap bubble solution
An undercharged system+insufficient airflow over the evaporator coil

34. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A sensing bulb improperly connected to the suction line
3 psig
Clean the condenser coil

35. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A sensing bulb improperly connected to the suction line
Low discharge pressure - high suction pressure - and low amp draw
Technician B

36. 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
An undercharged system+insufficient airflow over the evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

37. What causes the automatic expansion valve to close...
Evaporator and compressor
Both technicians are correct
An increase of air leakage from ductwork
An increase in low-side pressure

38. 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
110-120
Technician A
3 psig
20 to 30

39. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Contains a solenoid coil and one or more sets of contacts
20 to 30
The superheat increases and the subcooling decreases

40. Why is it unsafe to operate an air conditioning system with a low charge...
A restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
The superheat will increase and the low-side pressure will decrease

41. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Run with high head and high suction pressure
A start relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

42. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
The external equalizer could be plugged
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An acid-core suction line drier

43. A commercial customer calls on a 90
Both technicians are correct
It is used to control refrigerant pressure in the compressor crankcase
The system has been overcharged+The system has air trapped in the condenser
Partially frosted evaporator and high superheat

44. What is the purpose of a CPR valve...
Low voltage and a faulty start relay
It is used to control refrigerant pressure in the compressor crankcase
An increase in low-side pressure
Both technicians are incorrect

45. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Clean the condenser coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

46. 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
Partially frosted evaporator and high superheat
Broken rings+broken valves+seized bearings
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
High suction pressure and low superheat

47. 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
Lack of airflow
The external equalizer could be plugged
The sensing bulb at a lower temperature than the valve body
A low refrigerant charge

48. 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...
Evaporator and compressor
An uninsulated suction line and a restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Condenser fans operating during a low ambient condition and a low suction pressure

49. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
A start relay
Rise more than normal
Technician B

50. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Always have some liquid present in the bulb and diaphragm
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
110-120