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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 discharge temperature of an air-cooled air conditioning system that is used on a 90
Both technicians are correct
110-120
A missing air filter+improper rotation of the indoor blower+blower too small
The oil pump pressure and the crankcase pressure

2. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
A defective circuit breaker

3. A system that uses a thermal electric expansion valve...
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

4. 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...
20 to 30
High superheat and low discharge pressure
Bad compressor valve
The discharge pressure increases and the amperage increases

5. A restricted air filter in an air conditioning system can be identified by...
Technician B
Low superheat
Both technicians are incorrect
Technician B

6. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Contains a solenoid coil and one or more sets of contacts
Both technicians are correct
An acid-core suction line drier

7. 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...
Technician B
The internal overload is opened
A plugged filter drier
Short cycling and insufficient dehumidification

8. 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
A blown fuse
A restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small

9. The temperature range of the suction line from an air conditioning system should be...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated TXV sensing bulb
Low voltage and a faulty start relay
50-65

10. What are the symptoms of an air conditioning system that has a low charge...
Evaporator and compressor
Technician A is correct
The low-side pressure will decrease and the evaporator coil will be partially frosted
Lack of airflow

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
Technician B
Broken rings+broken valves+seized bearings
Technician A
50-65

12. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Low voltage and a faulty start relay
Flooding the condenser - cycling condenser fans - and dampering condenser air
Rise more than normal
Technician B

13. 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
It would cause the low-side pressure to decrease
Run with high head and high suction pressure
An open internal overload protector

14. 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
Whenever necessary
Short cycling and insufficient dehumidification
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B

15. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Condenser fans operating during a low ambient condition and a low suction pressure
110-120
Bad compressor valve
A defective circuit breaker

16. 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
Short cycling and insufficient dehumidification
An open internal overload protector
An undercharged system+insufficient airflow over the evaporator coil
High suction pressure and low superheat

17. A restricted air filter in an air conditioning system can be identified by...
Technician A is correct
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Low superheat
Current in the compressor circuit

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
Current in the compressor circuit
A bad thermostat
Low discharge pressure - high suction pressure - and low amp draw
The internal overload is opened

19. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...

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20. 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 plugged filter drier
Broken rings+broken valves+seized bearings
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B

21. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Both technicians are incorrect
Technician B
Low voltage and a faulty start relay

22. 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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23. 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...
A restricted metering device
Current in the compressor circuit
Condenser fans operating during a low ambient condition and a low suction pressure
The oil pump pressure and the crankcase pressure

24. What is the purpose of the TXV...
Always have some liquid present in the bulb and diaphragm
It keeps a constant superheat in the evaporator
Contains a solenoid coil and one or more sets of contacts
It would cause the low-side pressure to decrease

25. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
50-65
The sensing bulb at a lower temperature than the valve body
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease

26. Which of the following can cause excessive subcooling...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An overcharged system
Rise more than normal
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

27. 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
A blown fuse
Flooding the condenser - cycling condenser fans - and dampering condenser air
Both technicians are incorrect
A start relay

28. Which of the following could be the cause for a system's discharge and suction pressure being low...
A restricted metering device
Broken rings+broken valves+seized bearings
High superheat and low discharge pressure
The oil pump pressure and the crankcase pressure

29. Superheat is found in an air conditioning system in the...
Low superheat
Evaporator and compressor
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air

30. 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
High suction pressure and low superheat
The sensing bulb at a lower temperature than the valve body
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

31. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Low superheat
Condenser fans operating during a low ambient condition and a low suction pressure
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser

32. 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
Technician B
Both technicians are incorrect
The superheat increases and the subcooling decreases
A plugged filter drier

33. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Increases starting torque
Rise more than normal
3 psig
Partially frosted evaporator and high superheat

34. What are three methods for controlling a system's high-side pressure during low ambient conditions...
110-120
Flooding the condenser - cycling condenser fans - and dampering condenser air
A bad thermostat
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

35. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

36. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
An overcharged system
20 to 30
Clean the condenser coil
'G' to 'C'

37. Why is it unsafe to operate an air conditioning system with a low charge...
Evaporator and compressor
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The oil pump pressure and the crankcase pressure

38. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Run with high head and high suction pressure
An overcharged system
An acid-core suction line drier
'G' to 'C'

39. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated TXV sensing bulb
An uninsulated suction line and a restricted metering device
A vacuum test+oil traces around fittings+soap bubble solution

40. A liquid-charged TXV bulb will...
50-65
Always have some liquid present in the bulb and diaphragm
A bad thermostat
Contains a solenoid coil and one or more sets of contacts

41. 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
It would cause the low-side pressure to decrease
Technician B
The sensing bulb at a lower temperature than the valve body
110-120

42. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The sensing bulb at a lower temperature than the valve body
A vacuum test+oil traces around fittings+soap bubble solution
A missing air filter+improper rotation of the indoor blower+blower too small

43. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Bad compressor valve
Both technicians are incorrect
Both technicians are correct

44. 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
High superheat and low discharge pressure
The sensing bulb at a lower temperature than the valve body

45. 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 superheat will increase and the low-side pressure will decrease
Technician B
Always have some liquid present in the bulb and diaphragm
Contains a solenoid coil and one or more sets of contacts

46. 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 incorrect
A restricted metering device
Technician B
Both technicians are correct

47. When using a vapor-charged TXV bulb - it is necessary to have...
The internal overload is opened
The sensing bulb at a lower temperature than the valve body
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low superheat

48. When using a vapor-charged TXV bulb - it is necessary to have...
Low voltage and a faulty start relay
Technician B
The sensing bulb at a lower temperature than the valve body
20 to 30

49. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B

50. A compressor having tight bearings would cause the current value to...
3 psig
An uninsulated suction line and a restricted metering device
Technician A
Rise more than normal