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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 are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase in suction pressure and an increase in discharge pressure
An overcharged system
An overcharged system

2. What is the common cause of a compressor burnout...
Low discharge pressure - high suction pressure - and low amp draw
An uninsulated TXV sensing bulb
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

3. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
The low-side pressure will decrease and the evaporator coil will be partially frosted
'G' to 'C'
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Broken rings+broken valves+seized bearings

4. 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
An acid-core suction line drier
Bad compressor valve
Technician B
Partially frosted evaporator and high superheat

5. 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 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
An increase in suction pressure and an increase in discharge pressure
Broken rings+broken valves+seized bearings

6. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A vacuum test+oil traces around fittings+soap bubble solution
Flooding the condenser - cycling condenser fans - and dampering condenser air
An undercharge and low ambient conditions
An uninsulated suction line and a restricted metering device

7. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Clean the condenser coil
An undercharge and low ambient conditions
Low discharge pressure - high suction pressure - and low amp draw
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

8. 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
Both technicians are incorrect
A defective circuit breaker
The external equalizer could be plugged
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

9. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The external equalizer could be plugged
A bad thermostat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician A

10. 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
An overcharged system
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Whenever necessary

11. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Bad compressor valve
The external equalizer could be plugged
Condenser fans operating during a low ambient condition and a low suction pressure

12. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A restricted metering device
3 psig

13. 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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A vacuum test+oil traces around fittings+soap bubble solution
An uninsulated TXV sensing bulb
Both technicians are incorrect

14. 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
Technician B
An increase in suction pressure and an increase in discharge pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An open internal overload protector

15. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
3 psig
110-120
Contains a solenoid coil and one or more sets of contacts
An acid-core suction line drier

16. 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...
An overcharged system
The superheat will increase and the low-side pressure will decrease
High superheat and low discharge pressure
Both technicians are incorrect

17. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
'G' to 'C'
20 to 30
3 psig
110-120

18. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A start capacitor and a solid-state relay
A plugged filter drier
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A low refrigerant charge

19. 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
An uninsulated suction line and a restricted metering device
Low voltage and a faulty start relay
'G' to 'C'
Technician B

20. 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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Both technicians are incorrect
Increases starting torque
Technician B

21. 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
A defective circuit breaker
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device

22. 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
110-120
'G' to 'C'
Run with high head and high suction pressure
Technician B

23. A customer calls with an insufficient cooling complaint on a 90
A blown fuse
A start relay
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

24. 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...
The oil pump pressure and the crankcase pressure
A blown fuse
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

25. What is the purpose of an EPR valve...
Technician B
The discharge pressure increases and the amperage increases
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

26. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It keeps a constant superheat in the evaporator
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

27. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An increase in suction pressure and an increase in discharge pressure
An uninsulated TXV sensing bulb
3 psig
The discharge pressure increases and the amperage increases

28. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An acid-core suction line drier
Technician B

29. 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
It would cause the low-side pressure to decrease
50-65
Rise more than normal

30. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase in low-side pressure
An undercharge and low ambient conditions
A dirty condenser - recirculation of condenser air - and a defective condenser fan

31. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An uninsulated TXV sensing bulb

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

33. 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
The superheat increases and the subcooling decreases
An acid-core suction line drier
A low refrigerant charge
A bad thermostat

34. 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
Low discharge pressure - high suction pressure - and low amp draw
An overcharged system
Clean the condenser coil
3 psig

35. A restricted air filter in an air conditioning system can be identified by...
Low superheat
3 psig
Contains a solenoid coil and one or more sets of contacts
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

36. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Condenser fans operating during a low ambient condition and a low suction pressure
The system has been overcharged+The system has air trapped in the condenser

37. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Low superheat
('Y' and 'C') and ('G' and 'C')
A plugged filter drier

38. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The sensing bulb at a lower temperature than the valve body
3 psig
A sensing bulb improperly connected to the suction line
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

39. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
3 psig
A low refrigerant charge
It would cause the low-side pressure to decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

40. Which of the following could be the cause for a system's discharge and suction pressure being low...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A blown fuse
A restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser

41. A hard-start kit consists of...
A start capacitor and a solid-state relay
A blown fuse
It is used to control refrigerant pressure in the compressor crankcase
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

42. 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
Rise more than normal
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An undercharge and low ambient conditions

43. A commercial customer calls on a 90
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
An increase in suction pressure and an increase in discharge pressure
The system has been overcharged+The system has air trapped in the condenser

44. 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
The external equalizer could be plugged
An overcharged system
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

45. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An increase in low-side pressure
Current in the compressor circuit
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

46. A restricted air filter in an air conditioning system can be identified by...
Low superheat
The system has been overcharged+The system has air trapped in the condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air
Short cycling and insufficient dehumidification

47. The best description of a relay would be...
50-65
Contains a solenoid coil and one or more sets of contacts
An increase in low-side pressure
The internal overload is opened

48. A system that is operating with a clear sight glass shows...
The sight glass is full of liquid+the sight glass is full of gas
A start capacitor and a solid-state relay
An overcharged system
High superheat and low discharge pressure

49. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
A start capacitor and a solid-state relay
Technician B
An overcharged system

50. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Lack of airflow
An undercharge and low ambient conditions
An overcharged system