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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. Which of the following will cause excessive discharge pressures on an air conditioning system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
'G' to 'C'
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

2. A hard-start kit for an air conditioning system...
Condenser fans operating during a low ambient condition and a low suction pressure
Condenser fans operating during a low ambient condition and a low suction pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Increases starting torque

3. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The low-side pressure will decrease and the evaporator coil will be partially frosted

4. A system that uses a thermal electric expansion valve...
Technician B
A sensing bulb improperly connected to the suction line
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Bad compressor valve

5. A customer calls with an insufficient cooling complaint on a 90
Evaporator and compressor
20 to 30
Technician B
An uninsulated TXV sensing bulb

6. Which of the following could be the cause for a system's discharge and suction pressure being low...
Both technicians are correct
Evaporator and compressor
A restricted metering device
A sensing bulb improperly connected to the suction line

7. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Partially frosted evaporator and high superheat
3 psig
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
3 psig

8. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system has been overcharged+The system has air trapped in the condenser
An open internal overload protector
Flooding the condenser - cycling condenser fans - and dampering condenser air

9. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Run with high head and high suction pressure
A restricted metering device
Technician B
The discharge pressure increases and the amperage increases

10. 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...
An increase in low-side pressure
The internal overload is opened
Flooding the condenser - cycling condenser fans - and dampering condenser air
The external equalizer could be plugged

11. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Evaporator and compressor
Rise more than normal
20 to 30
50-65

12. What component is most often the cause of a start capacitor failure...
Increases starting torque
A start relay
An undercharged system+insufficient airflow over the evaporator coil
The superheat will increase and the low-side pressure will decrease

13. A hard-start kit for an air conditioning system...
Current in the compressor circuit
An undercharge and low ambient conditions
Increases starting torque
Both technicians are incorrect

14. 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
A bad thermostat
Technician A
('Y' and 'C') and ('G' and 'C')
A missing air filter+improper rotation of the indoor blower+blower too small

15. The best description of a relay would be...
Both technicians are correct
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Lack of airflow

16. 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
20 to 30
Technician B
Contains a solenoid coil and one or more sets of contacts
Dirty condenser - bent condenser fins - and air recirculating over the condenser

17. What problem or problems can cause low discharge and suction pressure...
The system has been overcharged+The system has air trapped in the condenser
An undercharged system+insufficient airflow over the evaporator coil
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An uninsulated suction line and a restricted metering device

18. A hard-start kit consists of...
A start capacitor and a solid-state relay
High suction pressure and low superheat
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

19. A system that is operating with a clear sight glass shows...
Low superheat
Current in the compressor circuit
Technician B
The sight glass is full of liquid+the sight glass is full of gas

20. 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
The system has been overcharged+The system has air trapped in the condenser
Clean the condenser coil
High superheat and low discharge pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan

21. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Partially frosted evaporator and high superheat
A defective circuit breaker
Technician B
The superheat increases and the subcooling decreases

22. 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
An increase in suction pressure and an increase in discharge pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

23. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
It would cause the low-side pressure to decrease
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An acid-core suction line drier
A restricted metering device

24. 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 system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
High superheat and low discharge pressure
The external equalizer could be plugged
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

25. 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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician A is correct
Clean the condenser coil

26. A split-system air conditioner that uses a piston-type metering device is to be charged with are-22. Technician A says that the outdoor dry-bulb temperature is needed to determine the proper superheat. Technician B says that the indoor wet-bulb tempe
Whenever necessary
The internal overload is opened
Bad compressor valve
Both technicians are correct

27. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
An increase in low-side pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
High suction pressure and low superheat
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

28. 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
Technician A is correct
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Contains a solenoid coil and one or more sets of contacts
The system has been overcharged+The system has air trapped in the condenser

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

30. What is the common cause of a compressor burnout...
Current in the compressor circuit
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A plugged filter drier
Low discharge pressure - high suction pressure - and low amp draw

31. 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
Lack of airflow
A plugged filter drier
Technician B
110-120

32. 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
Technician B
An overcharged system
It is used to control refrigerant pressure in the compressor crankcase

33. A customer calls with an insufficient cooling complaint on a 90
110-120
It is used to control refrigerant pressure in the compressor crankcase
Technician B
A vacuum test+oil traces around fittings+soap bubble solution

34. 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 internal overload is opened
Rise more than normal
A dirty condenser - recirculation of condenser air - and a defective condenser fan
High suction pressure and low superheat

35. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The sight glass is full of liquid+the sight glass is full of gas
50-65
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A low refrigerant charge

36. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
An overcharged system
Evaporator and compressor
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

37. What are the symptoms of a TXV air conditioning system if it has lost its charge...
'G' to 'C'
The system has been overcharged+The system has air trapped in the condenser
The superheat will increase and the low-side pressure will decrease
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

38. A restricted air filter in an air conditioning system can be identified by...
A plugged filter drier
Low superheat
The sight glass is full of liquid+the sight glass is full of gas
Technician B

39. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Whenever necessary
An increase in suction pressure and an increase in discharge pressure
A bad thermostat

40. 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...
High superheat and low discharge pressure
Technician A
An overcharged system
Both technicians are correct

41. A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that the outdoor condensing unit is operating - but the indoor blower is not in operation. Technician A says that it is possible that it is a bad fu
Technician B
The discharge pressure increases and the amperage increases
Both technicians are incorrect
A defective circuit breaker

42. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Contains a solenoid coil and one or more sets of contacts
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An overcharged system

43. A system that is operating with a clear sight glass shows...
The internal overload is opened
The sight glass is full of liquid+the sight glass is full of gas
Bad compressor valve
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

44. Why is it unsafe to operate an air conditioning system with a low charge...
20 to 30
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Partially frosted evaporator and high superheat
An increase in low-side pressure

45. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Always have some liquid present in the bulb and diaphragm
A restricted metering device
Broken rings+broken valves+seized bearings
Dirty condenser - bent condenser fins - and air recirculating over the condenser

46. 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 low refrigerant charge
Low superheat
Low voltage and a faulty start relay
A vacuum test+oil traces around fittings+soap bubble solution

47. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician A
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

48. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
110-120
A vacuum test+oil traces around fittings+soap bubble solution
An undercharge and low ambient conditions

49. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
A defective circuit breaker
An overcharged system
It keeps a constant superheat in the evaporator
Lack of airflow

50. Superheat is found in an air conditioning system in the...
Low discharge pressure - high suction pressure - and low amp draw
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Evaporator and compressor
The discharge pressure increases and the amperage increases