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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. 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
Technician B
Run with high head and high suction pressure
An undercharged system+insufficient airflow over the evaporator coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

2. What type of problems can be caused by an oversized air conditioning system...
It is used to control refrigerant pressure in the compressor crankcase
Short cycling and insufficient dehumidification
Low voltage and a faulty start relay
The sight glass is full of liquid+the sight glass is full of gas

3. What causes the automatic expansion valve to close...
An increase in low-side pressure
Clean the condenser coil
A plugged filter drier
A sensing bulb improperly connected to the suction line

4. Why is it unsafe to operate an air conditioning system with a low charge...
A missing air filter+improper rotation of the indoor blower+blower too small
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
The internal overload is opened

5. Why is it unsafe to operate an air conditioning system with a low charge...
It keeps a constant superheat in the evaporator
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
50-65

6. A system that is operating with a clear sight glass shows...
Broken rings+broken valves+seized bearings
The sight glass is full of liquid+the sight glass is full of gas
The discharge pressure increases and the amperage increases
Clean the condenser coil

7. 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 blown fuse
A defective circuit breaker
It is used to control refrigerant pressure in the compressor crankcase
Flooding the condenser - cycling condenser fans - and dampering condenser air

8. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
110-120
A start capacitor and a solid-state relay
Evaporator and compressor

9. 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
An uninsulated suction line and a restricted metering device
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
A low refrigerant charge

10. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
Both technicians are correct
An overcharged system
Whenever necessary

11. 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
Current in the compressor circuit
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Low superheat

12. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician A is correct
Short cycling and insufficient dehumidification
A plugged filter drier
'G' to 'C'

13. 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...
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
An increase of air leakage from ductwork
Dirty condenser - bent condenser fins - and air recirculating over the condenser

14. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Whenever necessary
It would cause the low-side pressure to decrease

15. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A start capacitor and a solid-state relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A bad thermostat

16. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Low superheat
A start capacitor and a solid-state relay

17. What problem or problems can cause low discharge and suction pressure...
A blown fuse
An undercharged system+insufficient airflow over the evaporator coil
Always have some liquid present in the bulb and diaphragm
20 to 30

18. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Rise more than normal
A blown fuse
Condenser fans operating during a low ambient condition and a low suction pressure

19. 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 superheat increases and the subcooling decreases
Technician A is correct
The superheat will increase and the low-side pressure will decrease
3 psig

20. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
A start relay
An overcharged system
An overcharged system

21. 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...
Both technicians are incorrect
Contains a solenoid coil and one or more sets of contacts
The internal overload is opened
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

22. 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...
Current in the compressor circuit
The oil pump pressure and the crankcase pressure
Contains a solenoid coil and one or more sets of contacts
Low voltage and a faulty start relay

23. 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
An increase in suction pressure and an increase in discharge pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Technician A is correct
Evaporator and compressor

24. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It keeps a constant superheat in the evaporator
It would cause the low-side pressure to decrease
Technician B
A plugged filter drier

25. A system that uses a thermal electric expansion valve...
Bad compressor valve
High superheat and low discharge pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect

26. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Always have some liquid present in the bulb and diaphragm
Increases starting torque
The internal overload is opened

27. A hard-start kit consists of...
High superheat and low discharge pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
A start capacitor and a solid-state relay

28. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Both technicians are correct
The discharge pressure increases and the amperage increases
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The internal overload is opened

29. 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
Run with high head and high suction pressure
Both technicians are correct
Technician B
The discharge pressure increases and the amperage increases

30. 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
Current in the compressor circuit
High suction pressure and low superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Clean the condenser coil

31. 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 undercharge and low ambient conditions
An uninsulated TXV sensing bulb
Technician B
Partially frosted evaporator and high superheat

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
The internal overload is opened
Contains a solenoid coil and one or more sets of contacts
Technician A

33. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician B
Run with high head and high suction pressure
A missing air filter+improper rotation of the indoor blower+blower too small
('Y' and 'C') and ('G' and 'C')

34. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
3 psig
An uninsulated TXV sensing bulb
20 to 30
Partially frosted evaporator and high superheat

35. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase in suction pressure and an increase in discharge pressure
It would cause the low-side pressure to decrease
An uninsulated suction line and a restricted metering device

36. 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
A restricted metering device
The external equalizer could be plugged
50-65
Partially frosted evaporator and high superheat

37. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Technician B
Run with high head and high suction pressure
Contains a solenoid coil and one or more sets of contacts
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

38. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
High suction pressure and low superheat
A restricted metering device
A plugged filter drier

39. Superheat is found in an air conditioning system in the...
Partially frosted evaporator and high superheat
Contains a solenoid coil and one or more sets of contacts
Whenever necessary
Evaporator and compressor

40. 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
An acid-core suction line drier
Run with high head and high suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A

41. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A bad thermostat
Technician A

42. 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
Both technicians are incorrect
An open internal overload protector
Technician B
Partially frosted evaporator and high superheat

43. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Technician A is correct
Dirty condenser - bent condenser fins - and air recirculating over the condenser
'G' to 'C'

44. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase

45. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An undercharge and low ambient conditions
A start capacitor and a solid-state relay
Both technicians are incorrect

46. 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
The system has been overcharged+The system has air trapped in the condenser
A blown fuse
An increase in low-side pressure
Technician B

47. 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
It keeps a constant superheat in the evaporator
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
The internal overload is opened

48. What is the purpose of an EPR valve...
A bad thermostat
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Bad compressor valve

49. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Short cycling and insufficient dehumidification
The system has been overcharged+The system has air trapped in the condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

50. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An acid-core suction line drier
The discharge pressure increases and the amperage increases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor