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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. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An uninsulated suction line and a restricted metering device
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The sight glass is full of liquid+the sight glass is full of gas
Technician A is correct

2. 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
Bad compressor valve
Technician B
Evaporator and compressor
Both technicians are incorrect

3. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
3 psig
Both technicians are incorrect
The external equalizer could be plugged

4. What is the purpose of a CPR valve...
It keeps a constant superheat in the evaporator
An overcharged system
Broken rings+broken valves+seized bearings
It is used to control refrigerant pressure in the compressor crankcase

5. Insufficient airflow can be caused by...
High suction pressure and low superheat
50-65
An increase of air leakage from ductwork
An increase in low-side pressure

6. A customer calls with an insufficient cooling complaint on a 90
Technician B
Low voltage and a faulty start relay
Partially frosted evaporator and high superheat
High suction pressure and low superheat

7. 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
Low discharge pressure - high suction pressure - and low amp draw
It would cause the low-side pressure to decrease
50-65
Technician B

8. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Broken rings+broken valves+seized bearings
Bad compressor valve
A bad thermostat
Rise more than normal

9. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Evaporator and compressor
It would cause the low-side pressure to decrease
An increase of air leakage from ductwork
Dirty condenser - bent condenser fins - and air recirculating over the condenser

10. A restricted air filter in an air conditioning system can be identified by...
Technician B
Low superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air
A plugged filter drier

11. 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 thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

12. A system that uses a thermal electric expansion valve...
An increase of air leakage from ductwork
An increase in suction pressure and an increase in discharge pressure
Current in the compressor circuit
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

13. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
110-120
Technician B

14. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
The oil pump pressure and the crankcase pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

15. Which of the following is a common cause of an excessively low superheat on a TXV system...
Both technicians are correct
A vacuum test+oil traces around fittings+soap bubble solution
A sensing bulb improperly connected to the suction line
Both technicians are incorrect

16. 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
Evaporator and compressor
Technician B
An overcharged system

17. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
The superheat increases and the subcooling decreases
Clean the condenser coil
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

18. 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 bad thermostat
A defective circuit breaker
50-65
Clean the condenser coil

19. A customer calls with an insufficient cooling complaint on a 90
A defective circuit breaker
An undercharged system+insufficient airflow over the evaporator coil
Both technicians are incorrect
Technician B

20. What type of problems can be caused by an oversized air conditioning system...
Both technicians are correct
A start capacitor and a solid-state relay
The sight glass is full of liquid+the sight glass is full of gas
Short cycling and insufficient dehumidification

21. What are the symptoms of a TXV air conditioning system if it has lost its charge...
The superheat will increase and the low-side pressure will decrease
A low refrigerant charge
Both technicians are correct
A blown fuse

22. When using a vapor-charged TXV bulb - it is necessary to have...
High superheat and low discharge pressure
50-65
The sensing bulb at a lower temperature than the valve body
A dirty condenser - recirculation of condenser air - and a defective condenser fan

23. The temperature range of the suction line from an air conditioning system should be...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Clean the condenser coil
Dirty condenser - bent condenser fins - and air recirculating over the condenser
50-65

24. What are three methods for controlling a system's high-side pressure during low ambient conditions...
High superheat and low discharge pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low voltage and a faulty start relay
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

25. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician A
A missing air filter+improper rotation of the indoor blower+blower too small

26. A commercial customer calls complaining that her rooftop air conditioning system is not operating. The technician arrives on the job and sets the thermostat to cooling - then notices that the indoor fan is not operating. The technician then sets the

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27. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
Flooding the condenser - cycling condenser fans - and dampering condenser air
Rise more than normal
'G' to 'C'

28. The internal overload of an air conditioning compressor senses winding temperature and...
Clean the condenser coil
Current in the compressor circuit
A blown fuse
Technician B

29. Why is it unsafe to operate an air conditioning system with a low charge...
The internal overload is opened
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It keeps a constant superheat in the evaporator

30. A system that is operating with a clear sight glass shows...
It keeps a constant superheat in the evaporator
High suction pressure and low superheat
The discharge pressure increases and the amperage increases
The sight glass is full of liquid+the sight glass is full of gas

31. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The discharge pressure increases and the amperage increases
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A low refrigerant charge
Whenever necessary

32. What are the operating pressures of an oil pressure safety switch...
An undercharged system+insufficient airflow over the evaporator coil
An undercharge and low ambient conditions
Rise more than normal
The oil pump pressure and the crankcase pressure

33. 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
Bad compressor valve
Both technicians are incorrect
Technician B
An increase in low-side pressure

34. A restricted air filter in an air conditioning system can be identified by...
A restricted metering device
The sensing bulb at a lower temperature than the valve body
Low superheat
An acid-core suction line drier

35. What type of problems can be caused by an oversized air conditioning system...
3 psig
An uninsulated TXV sensing bulb
Short cycling and insufficient dehumidification
An undercharge and low ambient conditions

36. 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 uninsulated TXV sensing bulb
Technician B
A low refrigerant charge
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

37. What are common methods that are used for leak-testing a system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
High suction pressure and low superheat
The superheat increases and the subcooling decreases
A vacuum test+oil traces around fittings+soap bubble solution

38. 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 bad thermostat
Low superheat
Low voltage and a faulty start relay
A missing air filter+improper rotation of the indoor blower+blower too small

39. A hard-start kit consists of...
A bad thermostat
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A start capacitor and a solid-state relay
The low-side pressure will decrease and the evaporator coil will be partially frosted

40. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A low refrigerant charge
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An uninsulated TXV sensing bulb
Technician B

41. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
The superheat will increase and the low-side pressure will decrease
3 psig
High suction pressure and low superheat
High suction pressure and low superheat

42. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Flooding the condenser - cycling condenser fans - and dampering condenser air
It keeps a constant superheat in the evaporator
50-65
An undercharge and low ambient conditions

43. 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
Both technicians are correct
A start relay
Low superheat
3 psig

44. What is the purpose of an EPR valve...
'G' to 'C'
Contains a solenoid coil and one or more sets of contacts
Evaporator and compressor
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

45. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An acid-core suction line drier
Technician A
The system has been overcharged+The system has air trapped in the condenser
It would cause the low-side pressure to decrease

46. What is the purpose of the TXV...
Both technicians are incorrect
It keeps a constant superheat in the evaporator
An increase in suction pressure and an increase in discharge pressure
Both technicians are incorrect

47. 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 oil pump pressure and the crankcase pressure
Broken rings+broken valves+seized bearings
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician A is correct

48. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The discharge pressure increases and the amperage increases
Current in the compressor circuit
Lack of airflow
Low superheat

49. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The superheat will increase and the low-side pressure will decrease
The discharge pressure increases and the amperage increases
An uninsulated TXV sensing bulb
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

50. 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...
Technician A
A blown fuse
The system has been overcharged+The system has air trapped in the condenser
Low voltage and a faulty start relay