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. 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
3 psig
An acid-core suction line drier
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

2. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Partially frosted evaporator and high superheat
Both technicians are incorrect
A start capacitor and a solid-state relay

3. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
An acid-core suction line drier
Short cycling and insufficient dehumidification
An uninsulated TXV sensing bulb
The discharge pressure increases and the amperage increases

4. What type of problems can be caused by an oversized air conditioning system...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An undercharged system+insufficient airflow over the evaporator coil
Clean the condenser coil
Short cycling and insufficient dehumidification

5. What are the operating pressures of an oil pressure safety switch...
It would cause the low-side pressure to decrease
The oil pump pressure and the crankcase pressure
110-120
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

6. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Technician B
Run with high head and high suction pressure
3 psig
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

7. 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
The external equalizer could be plugged
Low superheat
Technician B
Rise more than normal

8. A system that is operating with a clear sight glass shows...
Both technicians are correct
Increases starting torque
Lack of airflow
The sight glass is full of liquid+the sight glass is full of gas

9. What are the operating pressures of an oil pressure safety switch...
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
An increase in suction pressure and an increase in discharge pressure
The oil pump pressure and the crankcase pressure

10. What component is most often the cause of a start capacitor failure...
A start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A low refrigerant charge
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

11. 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
Bad compressor valve
The superheat increases and the subcooling decreases
'G' to 'C'

12. 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 start capacitor and a solid-state relay
Technician B
3 psig
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

13. 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 increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Rise more than normal
A plugged filter drier
Technician B

14. What is the common cause of a compressor burnout...
Partially frosted evaporator and high superheat
The system has been overcharged+The system has air trapped in the condenser
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

15. 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...
Technician B
The sight glass is full of liquid+the sight glass is full of gas
50-65
Condenser fans operating during a low ambient condition and a low suction pressure

16. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
The system has been overcharged+The system has air trapped in the condenser
The discharge pressure increases and the amperage increases
A restricted metering device

17. The internal overload of an air conditioning compressor senses winding temperature and...
Bad compressor valve
Condenser fans operating during a low ambient condition and a low suction pressure
Current in the compressor circuit
Rise more than normal

18. 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 blown fuse
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
Whenever necessary

19. What component is most often the cause of a start capacitor failure...
Run with high head and high suction pressure
The sensing bulb at a lower temperature than the valve body
Always have some liquid present in the bulb and diaphragm
A start relay

20. 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
The system has been overcharged+The system has air trapped in the condenser
Current in the compressor circuit
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician A

21. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start capacitor and a solid-state relay
The low-side pressure will decrease and the evaporator coil will be partially frosted

22. 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
('Y' and 'C') and ('G' and 'C')
The discharge pressure increases and the amperage increases
An acid-core suction line drier
A defective circuit breaker

23. Which of the following could be the cause for a system's discharge and suction pressure being low...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An open internal overload protector
A restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution

24. Why is it unsafe to operate an air conditioning system with a low charge...
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The sight glass is full of liquid+the sight glass is full of gas
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

25. 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
Contains a solenoid coil and one or more sets of contacts
Flooding the condenser - cycling condenser fans - and dampering condenser air
An uninsulated suction line and a restricted metering device

26. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low voltage and a faulty start relay
A plugged filter drier

27. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An overcharged system
An increase in low-side pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The internal overload is opened

28. 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
The oil pump pressure and the crankcase pressure
High superheat and low discharge pressure
A plugged filter drier

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
A bad thermostat
A blown fuse
Whenever necessary
Technician B

30. 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...
The external equalizer could be plugged
The internal overload is opened
The discharge pressure increases and the amperage increases
A start capacitor and a solid-state relay

31. Which of the following can cause excessive subcooling...
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
A defective circuit breaker
An overcharged system

32. What causes the automatic expansion valve to close...
Technician A
An increase in low-side pressure
20 to 30
An overcharged system

33. What are two common symptoms of refrigerant leaks in an air conditioning system...
3 psig
The superheat will increase and the low-side pressure will decrease
Lack of airflow
Partially frosted evaporator and high superheat

34. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
High superheat and low discharge pressure
Clean the condenser coil
Technician A is correct

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...
The internal overload is opened
High superheat and low discharge pressure
It would cause the low-side pressure to decrease
The system has been overcharged+The system has air trapped in the condenser

36. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
Increases starting torque
A blown fuse
It would cause the low-side pressure to decrease

37. What is the purpose of a CPR valve...
An increase of air leakage from ductwork
It is used to control refrigerant pressure in the compressor crankcase
Low superheat
An undercharge and low ambient conditions

38. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Broken rings+broken valves+seized bearings
The superheat increases and the subcooling decreases
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

39. 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 sensing bulb at a lower temperature than the valve body
Always have some liquid present in the bulb and diaphragm
Whenever necessary
A bad thermostat

40. A system that is operating with a clear sight glass shows...
An increase in suction pressure and an increase in discharge pressure
110-120
The sight glass is full of liquid+the sight glass is full of gas
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

41. 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 uninsulated TXV sensing bulb
Technician A is correct
20 to 30
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

42. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician B
It would cause the low-side pressure to decrease
Whenever necessary
An uninsulated suction line and a restricted metering device

43. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The internal overload is opened
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Run with high head and high suction pressure

44. A system that uses a thermal electric expansion valve...
Short cycling and insufficient dehumidification
Technician B
The sight glass is full of liquid+the sight glass is full of gas
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

45. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
'G' to 'C'
A bad thermostat
Bad compressor valve
An open internal overload protector

46. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A restricted metering device
Low voltage and a faulty start relay
Low superheat
Low discharge pressure - high suction pressure - and low amp draw

47. 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...
A defective circuit breaker
An uninsulated suction line and a restricted metering device
The superheat will increase and the low-side pressure will decrease
The internal overload is opened

48. 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
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air
High superheat and low discharge pressure
Low discharge pressure - high suction pressure - and low amp draw

49. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An undercharge and low ambient conditions

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...
Low voltage and a faulty start relay
Short cycling and insufficient dehumidification
A bad thermostat
It keeps a constant superheat in the evaporator