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. 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 oil pump pressure and the crankcase pressure
High suction pressure and low superheat
Broken rings+broken valves+seized bearings
Technician B

2. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A low refrigerant charge
It would cause the low-side pressure to decrease
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

3. A restricted air filter in an air conditioning system can be identified by...
Low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted
An increase in low-side pressure
'G' to 'C'

4. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A missing air filter+improper rotation of the indoor blower+blower too small
Technician A
Lack of airflow
A plugged filter drier

5. 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 thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A bad thermostat
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An acid-core suction line drier

6. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Technician A
High suction pressure and low superheat
The sensing bulb at a lower temperature than the valve body
An overcharged system

7. 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
An increase of air leakage from ductwork
A vacuum test+oil traces around fittings+soap bubble solution
Flooding the condenser - cycling condenser fans - and dampering condenser air

8. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A start capacitor and a solid-state relay
110-120
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

9. 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
Broken rings+broken valves+seized bearings
An increase of air leakage from ductwork
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

10. What are the symptoms of an air conditioning system that has a low charge...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

11. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Whenever necessary
Lack of airflow
Evaporator and compressor
Contains a solenoid coil and one or more sets of contacts

12. A liquid-charged TXV bulb will...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Increases starting torque
A start relay
Always have some liquid present in the bulb and diaphragm

13. Which of the following can cause low superheat in a TXV system...
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An uninsulated TXV sensing bulb
Always have some liquid present in the bulb and diaphragm

14. What are common methods that are used for leak-testing a system...
An open internal overload protector
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The low-side pressure will decrease and the evaporator coil will be partially frosted
A vacuum test+oil traces around fittings+soap bubble solution

15. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
The discharge pressure increases and the amperage increases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B

16. 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
A restricted metering device
It is used to control refrigerant pressure in the compressor crankcase
Technician B
Lack of airflow

17. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A bad thermostat
An increase in suction pressure and an increase in discharge pressure
An uninsulated suction line and a restricted metering device
Short cycling and insufficient dehumidification

18. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An acid-core suction line drier
A missing air filter+improper rotation of the indoor blower+blower too small
An open internal overload protector

19. 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
110-120
Increases starting torque
The sensing bulb at a lower temperature than the valve body

20. 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...
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
Technician A is correct
Low voltage and a faulty start relay

21. What is the purpose of a CPR valve...
An overcharged system
A missing air filter+improper rotation of the indoor blower+blower too small
It is used to control refrigerant pressure in the compressor crankcase
Run with high head and high suction pressure

22. A commercial customer calls on a 90
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A blown fuse
The system has been overcharged+The system has air trapped in the condenser
Technician A

23. What type of problems can be caused by an oversized air conditioning system...
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure

24. What are two common symptoms of refrigerant leaks in an air conditioning system...
Contains a solenoid coil and one or more sets of contacts
The sight glass is full of liquid+the sight glass is full of gas
Partially frosted evaporator and high superheat
Low voltage and a faulty start relay

25. 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 defective circuit breaker
Technician B
An overcharged system
Both technicians are incorrect

26. 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
Increases starting torque
An overcharged system
Technician A is correct

27. What type of problems can be caused by an oversized air conditioning system...
Both technicians are incorrect
('Y' and 'C') and ('G' and 'C')
Short cycling and insufficient dehumidification
Technician B

28. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The internal overload is opened
Always have some liquid present in the bulb and diaphragm
20 to 30
An increase in low-side pressure

29. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
('Y' and 'C') and ('G' and 'C')
Always have some liquid present in the bulb and diaphragm
Low discharge pressure - high suction pressure - and low amp draw
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

30. What is the purpose of an EPR valve...
Flooding the condenser - cycling condenser fans - and dampering condenser air
An increase in low-side pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

31. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharged system+insufficient airflow over the evaporator coil
Bad compressor valve
A missing air filter+improper rotation of the indoor blower+blower too small

32. 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...
Current in the compressor circuit
Technician A
An overcharged system
High superheat and low discharge pressure

33. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Evaporator and compressor
A sensing bulb improperly connected to the suction line

34. Why is it unsafe to operate an air conditioning system with a low charge...
An overcharged system
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician A is correct

35. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Technician B
An uninsulated TXV sensing bulb
It is used to control refrigerant pressure in the compressor crankcase
The discharge pressure increases and the amperage increases

36. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician A
Both technicians are incorrect

37. The internal overload of an air conditioning compressor senses winding temperature and...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The sensing bulb at a lower temperature than the valve body
Current in the compressor circuit

38. 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
An overcharged system
An undercharge and low ambient conditions
50-65

39. Which of the following is a possible cause for a compressor to overheat...
A restricted metering device
An increase in suction pressure and an increase in discharge pressure
A low refrigerant charge
It would cause the low-side pressure to decrease

40. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
A vacuum test+oil traces around fittings+soap bubble solution
Always have some liquid present in the bulb and diaphragm
Low superheat
Low discharge pressure - high suction pressure - and low amp draw

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
20 to 30
Technician A is correct
Bad compressor valve
Low superheat

42. Superheat is found in an air conditioning system in the...
Evaporator and compressor
High suction pressure and low superheat
The sight glass is full of liquid+the sight glass is full of gas
The internal overload is opened

43. 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
The internal overload is opened
An uninsulated suction line and a restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

44. What problem can cause an increase of discharge pressure and an increase of suction pressure...
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
An increase in suction pressure and an increase in discharge pressure
An overcharged system

45. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
'G' to 'C'
Current in the compressor circuit
('Y' and 'C') and ('G' and 'C')
3 psig

46. A system that is operating with a clear sight glass shows...
A blown fuse
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier
The discharge pressure increases and the amperage increases

47. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Both technicians are incorrect
('Y' and 'C') and ('G' and 'C')
Clean the condenser coil
A missing air filter+improper rotation of the indoor blower+blower too small

48. Which of the following is a common cause of an excessively low superheat on a TXV system...
20 to 30
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A sensing bulb improperly connected to the suction line
Contains a solenoid coil and one or more sets of contacts

49. A compressor having tight bearings would cause the current value to...
The internal overload is opened
A start capacitor and a solid-state relay
Rise more than normal
A blown fuse

50. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Both technicians are correct
Bad compressor valve
An open internal overload protector
Technician B