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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. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
An overcharged system
An acid-core suction line drier
The discharge pressure increases and the amperage increases

2. 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...

3. A restricted air filter in an air conditioning system can be identified by...
50-65
Low superheat
The discharge pressure increases and the amperage increases
Low discharge pressure - high suction pressure - and low amp draw

4. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
50-65
20 to 30
Technician A is correct
Short cycling and insufficient dehumidification

5. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An acid-core suction line drier
Flooding the condenser - cycling condenser fans - and dampering condenser air
Contains a solenoid coil and one or more sets of contacts
Low discharge pressure - high suction pressure - and low amp draw

6. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Bad compressor valve
The superheat increases and the subcooling decreases
A start capacitor and a solid-state relay
3 psig

7. Which of the following can cause low superheat in a TXV system...
Increases starting torque
Both technicians are correct
The system has been overcharged+The system has air trapped in the condenser
An uninsulated TXV sensing bulb

8. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
('Y' and 'C') and ('G' and 'C')
3 psig
Bad compressor valve

9. A hard-start kit consists of...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A start capacitor and a solid-state relay

10. 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 start capacitor and a solid-state relay
110-120
Bad compressor valve

11. 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
An acid-core suction line drier
An open internal overload protector
The internal overload is opened
Condenser fans operating during a low ambient condition and a low suction pressure

12. 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...

13. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
Rise more than normal
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B

14. What is the purpose of an EPR valve...
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Rise more than normal
The superheat increases and the subcooling decreases
Dirty condenser - bent condenser fins - and air recirculating over the condenser

15. A system that is operating with a clear sight glass shows...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
The superheat will increase and the low-side pressure will decrease
The sight glass is full of liquid+the sight glass is full of gas

16. Insufficient airflow can be caused by...
A low refrigerant charge
An increase of air leakage from ductwork
Technician B
The sensing bulb at a lower temperature than the valve body

17. 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 plugged filter drier
3 psig
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A bad thermostat

18. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
('Y' and 'C') and ('G' and 'C')
The system has been overcharged+The system has air trapped in the condenser

19. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
High suction pressure and low superheat
Lack of airflow
Always have some liquid present in the bulb and diaphragm
A blown fuse

20. 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
'G' to 'C'
The oil pump pressure and the crankcase pressure
The superheat increases and the subcooling decreases
Both technicians are incorrect

21. 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 external equalizer could be plugged
High superheat and low discharge pressure
Contains a solenoid coil and one or more sets of contacts
The internal overload is opened

22. 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
Low superheat
Technician B
A plugged filter drier
A bad thermostat

23. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Always have some liquid present in the bulb and diaphragm
Flooding the condenser - cycling condenser fans - and dampering condenser air
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low discharge pressure - high suction pressure - and low amp draw

24. What is the purpose of a CPR valve...
It would cause the low-side pressure to decrease
Run with high head and high suction pressure
It is used to control refrigerant pressure in the compressor crankcase
Condenser fans operating during a low ambient condition and a low suction pressure

25. What type of problems can be caused by an oversized air conditioning system...
An increase in low-side pressure
Technician B
Short cycling and insufficient dehumidification
Technician B

26. 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
Technician B
('Y' and 'C') and ('G' and 'C')
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

27. 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
An overcharged system
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The external equalizer could be plugged
Condenser fans operating during a low ambient condition and a low suction pressure

28. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Low superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The superheat increases and the subcooling decreases
('Y' and 'C') and ('G' and 'C')

29. Air filters should be replaced...
Evaporator and compressor
An increase of air leakage from ductwork
Whenever necessary
Contains a solenoid coil and one or more sets of contacts

30. 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
Partially frosted evaporator and high superheat
The system has been overcharged+The system has air trapped in the condenser
The low-side pressure will decrease and the evaporator coil will be partially frosted
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

31. A compressor having tight bearings would cause the current value to...
Rise more than normal
An increase in suction pressure and an increase in discharge pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Short cycling and insufficient dehumidification

32. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An increase in suction pressure and an increase in discharge pressure
An uninsulated suction line and a restricted metering device
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
The discharge pressure increases and the amperage increases

33. The internal overload of an air conditioning compressor senses winding temperature and...
Partially frosted evaporator and high superheat
It would cause the low-side pressure to decrease
Low superheat
Current in the compressor circuit

34. 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
A start relay
Both technicians are correct
Partially frosted evaporator and high superheat
The sight glass is full of liquid+the sight glass is full of gas

35. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
A missing air filter+improper rotation of the indoor blower+blower too small
An overcharged system
A restricted metering device
Run with high head and high suction pressure

36. Which of the following is a common cause of an excessively low superheat on a TXV system...
110-120
Both technicians are incorrect
A sensing bulb improperly connected to the suction line
The internal overload is opened

37. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
A low refrigerant charge
Technician B
An uninsulated suction line and a restricted metering device

38. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
The external equalizer could be plugged
A restricted metering device
Low superheat

39. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
3 psig
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
110-120

40. 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
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
Increases starting torque

41. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Both technicians are incorrect
High superheat and low discharge pressure
The discharge pressure increases and the amperage increases
A restricted metering device

42. What are the operating pressures of an oil pressure safety switch...
An increase in suction pressure and an increase in discharge pressure
The oil pump pressure and the crankcase pressure
A restricted metering device
Both technicians are incorrect

43. Why is it unsafe to operate an air conditioning system with a low charge...
An uninsulated TXV sensing bulb
Run with high head and high suction pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

44. 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...
50-65
Low voltage and a faulty start relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Always have some liquid present in the bulb and diaphragm

45. 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
An increase in suction pressure and an increase in discharge pressure
A sensing bulb improperly connected to the suction line
Both technicians are incorrect
The discharge pressure increases and the amperage increases

46. A restricted air filter in an air conditioning system can be identified by...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A start capacitor and a solid-state relay
Clean the condenser coil
Low superheat

47. Air filters should be replaced...
Low voltage and a faulty start relay
Current in the compressor circuit
Whenever necessary
A bad thermostat

48. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A plugged filter drier
Technician B

49. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
110-120
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
High suction pressure and low superheat

50. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
The sight glass is full of liquid+the sight glass is full of gas
An uninsulated suction line and a restricted metering device