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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. 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
An uninsulated TXV sensing bulb
Contains a solenoid coil and one or more sets of contacts
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan

2. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
The sight glass is full of liquid+the sight glass is full of gas
Lack of airflow
An increase in low-side pressure
Both technicians are correct

3. 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
110-120
The internal overload is opened
('Y' and 'C') and ('G' and 'C')

4. 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
Technician B
An acid-core suction line drier
Technician A
It keeps a constant superheat in the evaporator

5. 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
A sensing bulb improperly connected to the suction line
Technician B
Low superheat
Clean the condenser coil

6. What problem or problems can cause low discharge and suction pressure...
An undercharged system+insufficient airflow over the evaporator coil
The external equalizer could be plugged
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Bad compressor valve

7. 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 sight glass is full of liquid+the sight glass is full of gas
Clean the condenser coil
Both technicians are correct
High superheat and low discharge pressure

8. 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
An overcharged system
Technician B
Low voltage and a faulty start relay
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

9. Why is it unsafe to operate an air conditioning system with a low charge...
Flooding the condenser - cycling condenser fans - and dampering condenser air
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
Partially frosted evaporator and high superheat

10. What are two common symptoms of refrigerant leaks in an air conditioning system...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician A
Technician B
Partially frosted evaporator and high superheat

11. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
A defective circuit breaker
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Evaporator and compressor

12. What causes the automatic expansion valve to close...
An increase in low-side pressure
An acid-core suction line drier
110-120
A start relay

13. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

14. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
An acid-core suction line drier
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

15. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Low discharge pressure - high suction pressure - and low amp draw
Technician A
A plugged filter drier

16. A hard-start kit for an air conditioning system...
Increases starting torque
A plugged filter drier
A blown fuse
An undercharged system+insufficient airflow over the evaporator coil

17. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Rise more than normal
3 psig
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A sensing bulb improperly connected to the suction line

18. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
Both technicians are incorrect
High suction pressure and low superheat

19. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Clean the condenser coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

20. What component is most often the cause of a start capacitor failure...
A start relay
An undercharged system+insufficient airflow over the evaporator coil
Both technicians are correct
Both technicians are incorrect

21. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Clean the condenser coil
Flooding the condenser - cycling condenser fans - and dampering condenser air
A vacuum test+oil traces around fittings+soap bubble solution
The sight glass is full of liquid+the sight glass is full of gas

22. 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...
Bad compressor valve
Run with high head and high suction pressure
A blown fuse
Current in the compressor circuit

23. A restricted air filter in an air conditioning system can be identified by...
An acid-core suction line drier
Run with high head and high suction pressure
Both technicians are correct
Low superheat

24. A system that uses a thermal electric expansion valve...
Low voltage and a faulty start relay
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B

25. Which of the following can cause excessive subcooling...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Contains a solenoid coil and one or more sets of contacts
A start relay
An overcharged system

26. When using a vapor-charged TXV bulb - it is necessary to have...
Technician B
The sensing bulb at a lower temperature than the valve body
The external equalizer could be plugged
Partially frosted evaporator and high superheat

27. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A bad thermostat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Flooding the condenser - cycling condenser fans - and dampering condenser air

28. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
The external equalizer could be plugged
Technician B
An overcharged system

29. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
Condenser fans operating during a low ambient condition and a low suction pressure
The superheat will increase and the low-side pressure will decrease
Technician A is correct
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

30. 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
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An increase in low-side pressure
Lack of airflow

31. 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
It is used to control refrigerant pressure in the compressor crankcase
Bad compressor valve
Technician B
Both technicians are correct

32. 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
An increase in low-side pressure
Technician B
Technician A is correct
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

33. 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
Evaporator and compressor
20 to 30
Clean the condenser coil
An increase of air leakage from ductwork

34. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A start relay
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

35. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
('Y' and 'C') and ('G' and 'C')
Partially frosted evaporator and high superheat
A plugged filter drier
Increases starting torque

36. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
A missing air filter+improper rotation of the indoor blower+blower too small
It would cause the low-side pressure to decrease
Current in the compressor circuit
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

37. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Evaporator and compressor
50-65
An uninsulated suction line and a restricted metering device

38. Air filters should be replaced...
Technician B
Whenever necessary
A missing air filter+improper rotation of the indoor blower+blower too small
The superheat increases and the subcooling decreases

39. What type of problems can be caused by an oversized air conditioning system...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A start relay
Short cycling and insufficient dehumidification
A plugged filter drier

40. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
The superheat will increase and the low-side pressure will decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
'G' to 'C'
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

41. What is the purpose of the TXV...
It keeps a constant superheat in the evaporator
An uninsulated suction line and a restricted metering device
Technician A
A defective circuit breaker

42. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
An increase of air leakage from ductwork
Short cycling and insufficient dehumidification

43. When using a vapor-charged TXV bulb - it is necessary to have...
A defective circuit breaker
A vacuum test+oil traces around fittings+soap bubble solution
It would cause the low-side pressure to decrease
The sensing bulb at a lower temperature than the valve body

44. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
Technician B
The external equalizer could be plugged

45. 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...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Bad compressor valve
An uninsulated suction line and a restricted metering device
The internal overload is opened

46. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Rise more than normal
Current in the compressor circuit
Both technicians are incorrect

47. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Lack of airflow
Whenever necessary

48. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
An undercharge and low ambient conditions
A low refrigerant charge
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B

49. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Both technicians are incorrect
It is used to control refrigerant pressure in the compressor crankcase
Contains a solenoid coil and one or more sets of contacts
20 to 30

50. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
An undercharge and low ambient conditions
Technician A
An uninsulated TXV sensing bulb
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay