Test your basic knowledge |

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. 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
A missing air filter+improper rotation of the indoor blower+blower too small
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B

2. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
An undercharge and low ambient conditions
A sensing bulb improperly connected to the suction line
A plugged filter drier

3. What are two problems that can cause an air conditioning system to have an excessively high superheat...
A missing air filter+improper rotation of the indoor blower+blower too small
A blown fuse
110-120
An uninsulated suction line and a restricted metering device

4. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
Technician B
Low discharge pressure - high suction pressure - and low amp draw

5. 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...
Technician B
An overcharged system
Low voltage and a faulty start relay
Whenever necessary

6. What three things can prevent an air conditioning system from releasing heat at the proper rate...
An undercharged system+insufficient airflow over the evaporator coil
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

7. What is the purpose of a CPR valve...
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Clean the condenser coil
It is used to control refrigerant pressure in the compressor crankcase

8. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A plugged filter drier
An undercharge and low ambient conditions
Technician B

9. A hard-start kit for an air conditioning system...
Condenser fans operating during a low ambient condition and a low suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Increases starting torque
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

10. 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 superheat increases and the subcooling decreases
An uninsulated TXV sensing bulb
The external equalizer could be plugged
The low-side pressure will decrease and the evaporator coil will be partially frosted

11. The internal overload of an air conditioning compressor senses winding temperature and...
A missing air filter+improper rotation of the indoor blower+blower too small
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Broken rings+broken valves+seized bearings
Current in the compressor circuit

12. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An uninsulated suction line and a restricted metering device
50-65
An overcharged system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

13. What problem or problems can cause low discharge and suction pressure...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An undercharged system+insufficient airflow over the evaporator coil
The superheat will increase and the low-side pressure will decrease

14. 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
Low discharge pressure - high suction pressure - and low amp draw
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

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...
Low voltage and a faulty start relay
An acid-core suction line drier
Technician B
Short cycling and insufficient dehumidification

16. What are common methods that are used for leak-testing a system...
A missing air filter+improper rotation of the indoor blower+blower too small
The internal overload is opened
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

17. 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 sensing bulb improperly connected to the suction line
It keeps a constant superheat in the evaporator
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small

18. Why is it unsafe to operate an air conditioning system with a low charge...
'G' to 'C'
The oil pump pressure and the crankcase pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Flooding the condenser - cycling condenser fans - and dampering condenser air

19. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Current in the compressor circuit
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Broken rings+broken valves+seized bearings

20. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An increase in low-side pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
An undercharged system+insufficient airflow over the evaporator coil

21. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
Both technicians are incorrect
Always have some liquid present in the bulb and diaphragm
The internal overload is opened

22. Air filters should be replaced...
Evaporator and compressor
Whenever necessary
A low refrigerant charge
An uninsulated suction line and a restricted metering device

23. Air filters should be replaced...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Flooding the condenser - cycling condenser fans - and dampering condenser air
Whenever necessary
20 to 30

24. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Broken rings+broken valves+seized bearings
3 psig
A blown fuse

25. What problem or problems can cause low discharge and suction pressure...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated TXV sensing bulb
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An undercharged system+insufficient airflow over the evaporator coil

26. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
110-120
Technician B
Clean the condenser coil

27. 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
'G' to 'C'
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Run with high head and high suction pressure
Technician B

28. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Bad compressor valve
A low refrigerant charge
Technician A
An increase in suction pressure and an increase in discharge pressure

29. 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...
Whenever necessary
An increase in low-side pressure
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

30. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The sight glass is full of liquid+the sight glass is full of gas
The sensing bulb at a lower temperature than the valve body
Flooding the condenser - cycling condenser fans - and dampering condenser air
Increases starting torque

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
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
Technician B
Always have some liquid present in the bulb and diaphragm

32. What are the symptoms of a TXV air conditioning system if it has lost its charge...
A restricted metering device
An overcharged system
The superheat will increase and the low-side pressure will decrease
Evaporator and compressor

33. Which of the following is a possible cause for a compressor to overheat...
Both technicians are incorrect
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Both technicians are incorrect
A low refrigerant charge

34. A system that is operating with a clear sight glass shows...
Technician A
Technician B
High superheat and low discharge pressure
The sight glass is full of liquid+the sight glass is full of gas

35. 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 increase of air leakage from ductwork
The system has been overcharged+The system has air trapped in the condenser
High superheat and low discharge pressure
Contains a solenoid coil and one or more sets of contacts

36. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Current in the compressor circuit
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An undercharge and low ambient conditions

37. The temperature range of the suction line from an air conditioning system should be...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
High superheat and low discharge pressure
Low voltage and a faulty start relay
50-65

38. A liquid-charged TXV bulb will...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
Always have some liquid present in the bulb and diaphragm
High superheat and low discharge pressure

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 dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Current in the compressor circuit
Broken rings+broken valves+seized bearings

40. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An overcharged system
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air

41. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Both technicians are correct
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
A restricted metering device

42. What are the symptoms of an air conditioning system that has a low charge...
Low voltage and a faulty start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
110-120
The low-side pressure will decrease and the evaporator coil will be partially frosted

43. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
An uninsulated suction line and a restricted metering device
The external equalizer could be plugged
Broken rings+broken valves+seized bearings

44. Which of the following can cause excessive subcooling...
An overcharged system
A start relay
A low refrigerant charge
Flooding the condenser - cycling condenser fans - and dampering condenser air

45. A commercial customer calls on a 90
An increase of air leakage from ductwork
The system has been overcharged+The system has air trapped in the condenser
Both technicians are incorrect
50-65

46. What is the purpose of the TXV...
The discharge pressure increases and the amperage increases
The sight glass is full of liquid+the sight glass is full of gas
It keeps a constant superheat in the evaporator
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

47. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A sensing bulb improperly connected to the suction line
It would cause the low-side pressure to decrease
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

48. The internal overload of an air conditioning compressor senses winding temperature and...
Whenever necessary
Low discharge pressure - high suction pressure - and low amp draw
Technician B
Current in the compressor circuit

49. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
Technician A is correct
20 to 30

50. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A low refrigerant charge
Clean the condenser coil