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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. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A bad thermostat
Clean the condenser coil

2. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A defective circuit breaker
Clean the condenser coil
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The sensing bulb at a lower temperature than the valve body

3. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A bad thermostat
Partially frosted evaporator and high superheat
3 psig

4. 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
An undercharge and low ambient conditions
Technician B
It is used to control refrigerant pressure in the compressor crankcase

5. 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...
An uninsulated TXV sensing bulb
High superheat and low discharge pressure
Always have some liquid present in the bulb and diaphragm
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

6. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
A plugged filter drier
The low-side pressure will decrease and the evaporator coil will be partially frosted
Increases starting torque

7. What type of problems can be caused by an oversized air conditioning system...
A missing air filter+improper rotation of the indoor blower+blower too small
Technician A
Short cycling and insufficient dehumidification
A vacuum test+oil traces around fittings+soap bubble solution

8. 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 dirty condenser - recirculation of condenser air - and a defective condenser fan
Both technicians are incorrect
20 to 30
It keeps a constant superheat in the evaporator

9. A customer calls with an insufficient cooling complaint on a 90
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

10. A hard-start kit consists of...
A start capacitor and a solid-state relay
A blown fuse
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The oil pump pressure and the crankcase pressure

11. 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
3 psig
It would cause the low-side pressure to decrease
Broken rings+broken valves+seized bearings

12. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Clean the condenser coil
Lack of airflow
The internal overload is opened

13. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

14. A liquid-charged TXV bulb will...
High superheat and low discharge pressure
A start relay
It would cause the low-side pressure to decrease
Always have some liquid present in the bulb and diaphragm

15. What problem or problems can cause low discharge and suction pressure...
The system has been overcharged+The system has air trapped in the condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharged system+insufficient airflow over the evaporator coil

16. Which of the following will cause excessive discharge pressures on an air conditioning system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An overcharged system
3 psig
Technician B

17. 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...
Low voltage and a faulty start relay
Always have some liquid present in the bulb and diaphragm
A bad thermostat
Technician B

18. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
High suction pressure and low superheat
Technician B
20 to 30

19. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A plugged filter drier
Short cycling and insufficient dehumidification
('Y' and 'C') and ('G' and 'C')
20 to 30

20. The temperature range of the suction line from an air conditioning system should be...
A start relay
The oil pump pressure and the crankcase pressure
50-65
Both technicians are correct

21. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Evaporator and compressor
Increases starting torque
Technician B
Run with high head and high suction pressure

22. 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
Technician A
An increase in suction pressure and an increase in discharge pressure
An uninsulated TXV sensing bulb
Contains a solenoid coil and one or more sets of contacts

23. Which of the following could be the cause for a system's discharge and suction pressure being low...
Low voltage and a faulty start relay
Broken rings+broken valves+seized bearings
A restricted metering device
A missing air filter+improper rotation of the indoor blower+blower too small

24. 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
Clean the condenser coil
The oil pump pressure and the crankcase pressure
An uninsulated suction line and a restricted metering device
The external equalizer could be plugged

25. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
The superheat will increase and the low-side pressure will decrease
A low refrigerant charge
An undercharge and low ambient conditions
The external equalizer could be plugged

26. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

27. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Rise more than normal
A bad thermostat
A restricted metering device
It would cause the low-side pressure to decrease

28. 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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29. What is the purpose of the TXV...
A vacuum test+oil traces around fittings+soap bubble solution
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system has been overcharged+The system has air trapped in the condenser
It keeps a constant superheat in the evaporator

30. 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
Low voltage and a faulty start relay
It would cause the low-side pressure to decrease

31. 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
Low superheat
Lack of airflow
3 psig
Both technicians are incorrect

32. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
The superheat increases and the subcooling decreases
Always have some liquid present in the bulb and diaphragm
A vacuum test+oil traces around fittings+soap bubble solution
20 to 30

33. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The discharge pressure increases and the amperage increases
Technician A is correct
Low voltage and a faulty start relay

34. 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...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The internal overload is opened
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Condenser fans operating during a low ambient condition and a low suction pressure

35. 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
A plugged filter drier
Technician B
Broken rings+broken valves+seized bearings
An overcharged system

36. 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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37. A hard-start kit for an air conditioning system...
It keeps a constant superheat in the evaporator
Increases starting torque
The external equalizer could be plugged
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

38. 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 sensing bulb improperly connected to the suction line
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A restricted metering device

39. 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 defective circuit breaker
The sight glass is full of liquid+the sight glass is full of gas
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Technician B

40. 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
Low superheat
A plugged filter drier

41. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are correct
An increase of air leakage from ductwork
Technician B

42. 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
A bad thermostat
Technician B
Both technicians are incorrect
The system has been overcharged+The system has air trapped in the condenser

43. A hard-start kit for an air conditioning system...
Increases starting torque
Clean the condenser coil
An increase in suction pressure and an increase in discharge pressure
Low superheat

44. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
3 psig

45. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
Technician B
Low superheat
Broken rings+broken valves+seized bearings

46. 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
A vacuum test+oil traces around fittings+soap bubble solution
Contains a solenoid coil and one or more sets of contacts
Technician A

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
Technician A
Short cycling and insufficient dehumidification
An increase in low-side pressure
An undercharged system+insufficient airflow over the evaporator coil

48. What component is most often the cause of a start capacitor failure...
Rise more than normal
A start relay
Partially frosted evaporator and high superheat
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

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 internal overload is opened
A sensing bulb improperly connected to the suction line
A bad thermostat
The superheat will increase and the low-side pressure will decrease

50. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
The sight glass is full of liquid+the sight glass is full of gas
Increases starting torque
A blown fuse
Dirty condenser - bent condenser fins - and air recirculating over the condenser