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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 releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are correct
3 psig
Always have some liquid present in the bulb and diaphragm

2. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
The sensing bulb at a lower temperature than the valve body
An undercharged system+insufficient airflow over the evaporator coil
An overcharged system

3. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Clean the condenser coil
An undercharge and low ambient conditions
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

4. 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
Low superheat
The sight glass is full of liquid+the sight glass is full of gas

5. 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
An open internal overload protector
Clean the condenser coil
An undercharged system+insufficient airflow over the evaporator coil
An undercharged system+insufficient airflow over the evaporator coil

6. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Evaporator and compressor
Technician B
An uninsulated TXV sensing bulb

7. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It would cause the low-side pressure to decrease
High suction pressure and low superheat

8. 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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9. 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 refrigerant charge
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
A restricted metering device

10. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A vacuum test+oil traces around fittings+soap bubble solution
High suction pressure and low superheat
Both technicians are correct
Low superheat

11. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Rise more than normal
The superheat will increase and the low-side pressure will decrease
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase in suction pressure and an increase in discharge pressure

12. Insufficient airflow can be caused by...
Low superheat
110-120
An undercharge and low ambient conditions
An increase of air leakage from ductwork

13. 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 restricted metering device
An acid-core suction line drier
Technician A
A start capacitor and a solid-state relay

14. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Technician A is correct
110-120
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

15. 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 blown fuse
A low refrigerant charge
Technician B
Technician A is correct

16. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Increases starting torque
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The superheat will increase and the low-side pressure will decrease

17. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician A is correct
50-65

18. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
A bad thermostat
Low voltage and a faulty start relay
A start capacitor and a solid-state relay

19. 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
An increase in low-side pressure
Evaporator and compressor
Clean the condenser coil
Technician B

20. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
20 to 30
A plugged filter drier
Flooding the condenser - cycling condenser fans - and dampering condenser air
50-65

21. A hard-start kit for an air conditioning system...
Increases starting torque
A blown fuse
The discharge pressure increases and the amperage increases
'G' to 'C'

22. A hard-start kit consists of...
High superheat and low discharge pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A blown fuse
A start capacitor and a solid-state relay

23. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
A bad thermostat
Technician B
Contains a solenoid coil and one or more sets of contacts

24. Insufficient airflow can be caused by...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An increase of air leakage from ductwork
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The superheat will increase and the low-side pressure will decrease

25. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
3 psig
A start relay
The system has been overcharged+The system has air trapped in the condenser

26. The temperature range of the suction line from an air conditioning system should be...
Current in the compressor circuit
Technician B
50-65
Rise more than normal

27. What is the purpose of a CPR valve...
An increase in low-side pressure
Short cycling and insufficient dehumidification
It is used to control refrigerant pressure in the compressor crankcase
The superheat increases and the subcooling decreases

28. A technician receives an air conditioning service call stating that the system is operating but isn't cooling properly. When the technician arrives - she notices that the compressor has recently been changed and it is an are-22 system. She checks the
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start capacitor and a solid-state relay
Whenever necessary
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

29. 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
50-65
An increase in low-side pressure
A defective circuit breaker
Always have some liquid present in the bulb and diaphragm

30. What are two common symptoms of refrigerant leaks in an air conditioning system...
A vacuum test+oil traces around fittings+soap bubble solution
Technician B
A blown fuse
Partially frosted evaporator and high superheat

31. A commercial customer calls on a 90
High suction pressure and low superheat
The oil pump pressure and the crankcase pressure
The system has been overcharged+The system has air trapped in the condenser
An overcharged system

32. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Bad compressor valve
Whenever necessary

33. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Short cycling and insufficient dehumidification
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
An overcharged system

34. 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
Low superheat
A bad thermostat
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

35. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Both technicians are incorrect
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The superheat increases and the subcooling decreases
A plugged filter drier

36. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A blown fuse
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

37. What is the purpose of an EPR valve...
A start relay
An increase of air leakage from ductwork
Current in the compressor circuit
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

38. 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
Low superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Whenever necessary
Technician B

39. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
Both technicians are incorrect
The sensing bulb at a lower temperature than the valve body
It is used to control refrigerant pressure in the compressor crankcase

40. Which of the following will cause excessive discharge pressures on an air conditioning system...
High superheat and low discharge pressure
A start relay
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

41. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A sensing bulb improperly connected to the suction line
Run with high head and high suction pressure
The superheat increases and the subcooling decreases
A sensing bulb improperly connected to the suction line

42. 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
The system has been overcharged+The system has air trapped in the condenser
An overcharged system
Clean the condenser coil
An open internal overload protector

43. Which of the following will cause excessive discharge pressures on an air conditioning system...
Short cycling and insufficient dehumidification
A blown fuse
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Low superheat

44. What is the purpose of an EPR valve...
A restricted metering device
A sensing bulb improperly connected to the suction line
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Always have some liquid present in the bulb and diaphragm

45. Which of the following is a possible cause for a compressor to overheat...
High suction pressure and low superheat
50-65
A defective circuit breaker
A low refrigerant charge

46. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
It is used to control refrigerant pressure in the compressor crankcase
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An increase in suction pressure and an increase in discharge pressure
The superheat will increase and the low-side pressure will decrease

47. 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
3 psig
Increases starting torque
20 to 30

48. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
An acid-core suction line drier
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An increase in low-side pressure

49. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Both technicians are incorrect
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An increase in suction pressure and an increase in discharge pressure
Both technicians are correct

50. What problem or problems can cause low discharge and suction pressure...
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque
An undercharged system+insufficient airflow over the evaporator coil
Bad compressor valve