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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. 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...
A blown fuse
'G' to 'C'
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Partially frosted evaporator and high superheat

2. Which of the following is a possible cause for a compressor to overheat...
An overcharged system
The discharge pressure increases and the amperage increases
A low refrigerant charge
The sensing bulb at a lower temperature than the valve body

3. The temperature range of the suction line from an air conditioning system should be...
The discharge pressure increases and the amperage increases
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
50-65

4. 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
A plugged filter drier
It is used to control refrigerant pressure in the compressor crankcase
The low-side pressure will decrease and the evaporator coil will be partially frosted

5. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
110-120
An acid-core suction line drier
Partially frosted evaporator and high superheat
A plugged filter drier

6. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A blown fuse
20 to 30
Both technicians are correct
Increases starting torque

7. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

8. What is the common cause of a compressor burnout...
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The sight glass is full of liquid+the sight glass is full of gas
Increases starting torque

9. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Low superheat
50-65
A start relay
The superheat will increase and the low-side pressure will decrease

10. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
'G' to 'C'
The external equalizer could be plugged
Low voltage and a faulty start relay

11. Which of the following could be the cause for a system's discharge and suction pressure being low...
An acid-core suction line drier
A restricted metering device
Evaporator and compressor
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

12. 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...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
The internal overload is opened

13. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Broken rings+broken valves+seized bearings
20 to 30
Run with high head and high suction pressure
An overcharged system

14. Why is it unsafe to operate an air conditioning system with a low charge...
Both technicians are correct
110-120
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

15. Which of the following will cause excessive discharge pressures on an air conditioning system...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect

16. A system that uses a thermal electric expansion valve...
Rise more than normal
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
The sensing bulb at a lower temperature than the valve body

17. The best description of a relay would be...
An increase in low-side pressure
Whenever necessary
A start capacitor and a solid-state relay
Contains a solenoid coil and one or more sets of contacts

18. 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
A low refrigerant charge
The external equalizer could be plugged
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

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
The sensing bulb at a lower temperature than the valve body
Low superheat
The external equalizer could be plugged
Technician B

20. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
110-120
Technician B
An increase of air leakage from ductwork

21. What are the symptoms of an air conditioning system that has a low charge...
Technician B
The discharge pressure increases and the amperage increases
The low-side pressure will decrease and the evaporator coil will be partially frosted
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

22. What are two common symptoms of refrigerant leaks in an air conditioning system...
A blown fuse
The oil pump pressure and the crankcase pressure
The discharge pressure increases and the amperage increases
Partially frosted evaporator and high superheat

23. A liquid-charged TXV bulb will...
An increase in suction pressure and an increase in discharge pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Always have some liquid present in the bulb and diaphragm
The oil pump pressure and the crankcase pressure

24. What is the purpose of a CPR valve...
A blown fuse
It is used to control refrigerant pressure in the compressor crankcase
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
'G' to 'C'

25. 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
The oil pump pressure and the crankcase pressure
Clean the condenser coil
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

26. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
3 psig

27. A compressor having tight bearings would cause the current value to...
Rise more than normal
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

28. 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
Bad compressor valve
High superheat and low discharge pressure
Clean the condenser coil
Run with high head and high suction pressure

29. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The sensing bulb at a lower temperature than the valve body
An undercharged system+insufficient airflow over the evaporator coil
Rise more than normal
A dirty condenser - recirculation of condenser air - and a defective condenser fan

30. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The superheat increases and the subcooling decreases
A bad thermostat
Bad compressor valve
The system has been overcharged+The system has air trapped in the condenser

31. A restricted air filter in an air conditioning system can be identified by...
Technician B
50-65
Low superheat
Short cycling and insufficient dehumidification

32. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
3 psig
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
110-120
Increases starting torque

33. 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
3 psig
Rise more than normal
Evaporator and compressor
Both technicians are correct

34. 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

35. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Run with high head and high suction pressure
Low superheat
A missing air filter+improper rotation of the indoor blower+blower too small
Technician B

36. What component is most often the cause of a start capacitor failure...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The internal overload is opened
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A start relay

37. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Both technicians are correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A sensing bulb improperly connected to the suction line
Both technicians are correct

38. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Technician B
Both technicians are correct
Technician B
It would cause the low-side pressure to decrease

39. What are the operating pressures of an oil pressure safety switch...
An increase in low-side pressure
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
High superheat and low discharge pressure
The oil pump pressure and the crankcase pressure

40. What are the symptoms of an air conditioning system that has a low charge...
The low-side pressure will decrease and the evaporator coil will be partially frosted
The superheat increases and the subcooling decreases
Technician B
An increase in suction pressure and an increase in discharge pressure

41. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
It is used to control refrigerant pressure in the compressor crankcase
An uninsulated TXV sensing bulb
Run with high head and high suction pressure

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
A blown fuse
Technician B
110-120

43. 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
An overcharged system
The sight glass is full of liquid+the sight glass is full of gas
Clean the condenser coil

44. 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
Contains a solenoid coil and one or more sets of contacts
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A defective circuit breaker

45. What causes the automatic expansion valve to close...
Both technicians are incorrect
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

46. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Both technicians are correct
An uninsulated suction line and a restricted metering device
Flooding the condenser - cycling condenser fans - and dampering condenser air
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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Both technicians are incorrect
High superheat and low discharge pressure

48. Which of the following could be the cause for a system's discharge and suction pressure being low...
Technician B
A restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An increase of air leakage from ductwork

49. Which of the following is a common cause of an excessively low superheat on a TXV system...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An uninsulated suction line and a restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A sensing bulb improperly connected to the suction line

50. 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
Lack of airflow
Whenever necessary
A bad thermostat
20 to 30