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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 is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Technician B
A sensing bulb improperly connected to the suction line
20 to 30
A bad thermostat

2. What are the symptoms of an air conditioning system that has a low charge...
An undercharge and low ambient conditions
Contains a solenoid coil and one or more sets of contacts
The low-side pressure will decrease and the evaporator coil will be partially frosted
20 to 30

3. A system that is operating with a clear sight glass shows...
An undercharged system+insufficient airflow over the evaporator coil
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas
A start relay

4. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Evaporator and compressor
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system

5. 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
Both technicians are incorrect
A start capacitor and a solid-state relay
An undercharged system+insufficient airflow over the evaporator coil
A plugged filter drier

6. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Short cycling and insufficient dehumidification

7. What type of problems can be caused by an oversized air conditioning system...
Evaporator and compressor
Short cycling and insufficient dehumidification
An overcharged system
A dirty condenser - recirculation of condenser air - and a defective condenser fan

8. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The external equalizer could be plugged
Evaporator and compressor
Low superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan

9. What causes the automatic expansion valve to close...
The oil pump pressure and the crankcase pressure
An increase in low-side pressure
Clean the condenser coil
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

10. What component is most often the cause of a start capacitor failure...
Low voltage and a faulty start relay
Broken rings+broken valves+seized bearings
Technician A is correct
A start relay

11. The best description of a relay would be...
It keeps a constant superheat in the evaporator
Technician B
Low voltage and a faulty start relay
Contains a solenoid coil and one or more sets of contacts

12. A commercial customer calls on a 90
A plugged filter drier
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
The system has been overcharged+The system has air trapped in the condenser

13. 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
Both technicians are correct
The external equalizer could be plugged
An uninsulated TXV sensing bulb
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

14. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
The external equalizer could be plugged
Technician B
Run with high head and high suction pressure
The discharge pressure increases and the amperage increases

15. What are three methods for controlling a system's high-side pressure during low ambient conditions...
The oil pump pressure and the crankcase pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
A blown fuse
Technician B

16. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Both technicians are incorrect
Lack of airflow
Whenever necessary
Rise more than normal

17. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
'G' to 'C'
Dirty condenser - bent condenser fins - and air recirculating over the condenser
High suction pressure and low superheat
A dirty condenser - recirculation of condenser air - and a defective condenser fan

18. 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...
The external equalizer could be plugged
Clean the condenser coil
Condenser fans operating during a low ambient condition and a low suction pressure
An overcharged system

19. 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
High suction pressure and low superheat
A low refrigerant charge
Technician B
Short cycling and insufficient dehumidification

20. 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 oil pump pressure and the crankcase pressure
Clean the condenser coil
High superheat and low discharge pressure
A defective circuit breaker

21. 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
Contains a solenoid coil and one or more sets of contacts
Technician A
Current in the compressor circuit
A restricted metering device

22. 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
A bad thermostat
A start capacitor and a solid-state relay
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

23. 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
The sight glass is full of liquid+the sight glass is full of gas
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Dirty condenser - bent condenser fins - and air recirculating over the condenser

24. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Bad compressor valve
110-120
High superheat and low discharge pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

25. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Clean the condenser coil
An overcharged system

26. 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
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 open internal overload protector
Both technicians are incorrect

27. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Rise more than normal
Run with high head and high suction pressure
An acid-core suction line drier
A defective circuit breaker

28. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
Flooding the condenser - cycling condenser fans - and dampering condenser air
An increase in low-side pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

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
A defective circuit breaker
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician A

30. 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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31. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Technician B
A blown fuse
20 to 30
An increase in suction pressure and an increase in discharge pressure

32. When using a vapor-charged TXV bulb - it is necessary to have...
Run with high head and high suction pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Rise more than normal
The sensing bulb at a lower temperature than the valve body

33. 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
A bad thermostat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Short cycling and insufficient dehumidification
The low-side pressure will decrease and the evaporator coil will be partially frosted

34. 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
Technician B
('Y' and 'C') and ('G' and 'C')
The oil pump pressure and the crankcase pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

35. A compressor having tight bearings would cause the current value to...
An increase in low-side pressure
A start relay
The discharge pressure increases and the amperage increases
Rise more than normal

36. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The superheat increases and the subcooling decreases
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

37. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
Current in the compressor circuit
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

38. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Short cycling and insufficient dehumidification
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A vacuum test+oil traces around fittings+soap bubble solution

39. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
An uninsulated suction line and a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
('Y' and 'C') and ('G' and 'C')

40. Which of the following can cause low superheat in a TXV system...
Clean the condenser coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
High superheat and low discharge pressure
An uninsulated TXV sensing bulb

41. 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
The oil pump pressure and the crankcase pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

42. What is the purpose of a CPR valve...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
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
It is used to control refrigerant pressure in the compressor crankcase

43. 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 B
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician A is correct

44. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
A low refrigerant charge
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit

45. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Bad compressor valve
An overcharged system
('Y' and 'C') and ('G' and 'C')
Low voltage and a faulty start relay

46. What is the common cause of a compressor burnout...
The system has been overcharged+The system has air trapped in the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system

47. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
An undercharged system+insufficient airflow over the evaporator coil
Evaporator and compressor
Lack of airflow

48. A hard-start kit for an air conditioning system...
Low superheat
A restricted metering device
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Increases starting torque

49. 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 discharge pressure increases and the amperage increases
A bad thermostat
The sight glass is full of liquid+the sight glass is full of gas
Technician B

50. A system that uses a thermal electric expansion valve...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Flooding the condenser - cycling condenser fans - and dampering condenser air
Short cycling and insufficient dehumidification