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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 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 increase in low-side pressure
Low voltage and a faulty start relay
('Y' and 'C') and ('G' and 'C')
High superheat and low discharge pressure

2. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
The superheat will increase and the low-side pressure will decrease
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A defective circuit breaker
High suction pressure and low superheat

3. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
The discharge pressure increases and the amperage increases
Low voltage and a faulty start relay
An undercharged system+insufficient airflow over the evaporator coil
The low-side pressure will decrease and the evaporator coil will be partially frosted

4. What is the common cause of a compressor burnout...
Evaporator and compressor
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A plugged filter drier
It would cause the low-side pressure to decrease

5. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The sensing bulb at a lower temperature than the valve body
Both technicians are incorrect
Flooding the condenser - cycling condenser fans - and dampering condenser air

6. 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
A restricted metering device
A start relay
Flooding the condenser - cycling condenser fans - and dampering condenser air

7. The temperature range of the suction line from an air conditioning system should be...
Both technicians are incorrect
Both technicians are incorrect
50-65
Low discharge pressure - high suction pressure - and low amp draw

8. A hard-start kit for an air conditioning system...
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are incorrect
Increases starting torque

9. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
20 to 30
A missing air filter+improper rotation of the indoor blower+blower too small

10. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Contains a solenoid coil and one or more sets of contacts
Technician A
3 psig

11. 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
It keeps a constant superheat in the evaporator
An increase of air leakage from ductwork
A bad thermostat

12. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
The external equalizer could be plugged
The sight glass is full of liquid+the sight glass is full of gas
A start capacitor and a solid-state relay

13. 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 dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Partially frosted evaporator and high superheat
An increase in suction pressure and an increase in discharge pressure

14. 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...
Always have some liquid present in the bulb and diaphragm
High superheat and low discharge pressure
Run with high head and high suction pressure
Condenser fans operating during a low ambient condition and a low suction pressure

15. 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
A defective circuit breaker
An overcharged system
Short cycling and insufficient dehumidification

16. A customer calls with an insufficient cooling complaint on a 90
Technician B
Broken rings+broken valves+seized bearings
Always have some liquid present in the bulb and diaphragm
The low-side pressure will decrease and the evaporator coil will be partially frosted

17. A compressor having tight bearings would cause the current value to...
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
A defective circuit breaker
Rise more than normal

18. 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 has been overcharged+The system has air trapped in the condenser
A start capacitor and a solid-state relay
Technician B
Both technicians are incorrect

19. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
The sight glass is full of liquid+the sight glass is full of gas
Run with high head and high suction pressure
50-65

20. A system that uses a thermal electric expansion valve...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
('Y' and 'C') and ('G' and 'C')
20 to 30
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

21. 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
Increases starting torque
Technician B
Technician B

22. A restricted air filter in an air conditioning system can be identified by...
Technician B
It would cause the low-side pressure to decrease
Low superheat
Run with high head and high suction pressure

23. When using a vapor-charged TXV bulb - it is necessary to have...
Always have some liquid present in the bulb and diaphragm
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
It keeps a constant superheat in the evaporator
The sensing bulb at a lower temperature than the valve body

24. A system that is operating with a clear sight glass shows...
A defective circuit breaker
It is used to control refrigerant pressure in the compressor crankcase
The sight glass is full of liquid+the sight glass is full of gas
Low voltage and a faulty start relay

25. What causes the automatic expansion valve to close...
A sensing bulb improperly connected to the suction line
Low superheat
An increase in low-side pressure
Whenever necessary

26. What are the operating pressures of an oil pressure safety switch...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The oil pump pressure and the crankcase pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
Rise more than normal

27. What is the purpose of the TXV...
An increase in low-side pressure
It keeps a constant superheat in the evaporator
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B

28. Why is it unsafe to operate an air conditioning system with a low charge...
An undercharge and low ambient conditions
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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

29. 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...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
A blown fuse
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

30. 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
3 psig
The external equalizer could be plugged
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B

31. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Broken rings+broken valves+seized bearings
Clean the condenser coil
Low superheat
Low discharge pressure - high suction pressure - and low amp draw

32. A customer calls with an insufficient cooling complaint on a 90
The low-side pressure will decrease and the evaporator coil will be partially frosted
A sensing bulb improperly connected to the suction line
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

33. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
An increase in low-side pressure
Technician B
Low superheat

34. What is the common cause of a compressor burnout...
An undercharge and low ambient conditions
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

35. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Both technicians are incorrect
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A restricted metering device

36. 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
A vacuum test+oil traces around fittings+soap bubble solution
Rise more than normal
Low voltage and a faulty start relay
Technician B

37. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
A plugged filter drier
20 to 30

38. What are the symptoms of an air conditioning system that has a low charge...
A bad thermostat
The discharge pressure increases and the amperage increases
20 to 30
The low-side pressure will decrease and the evaporator coil will be partially frosted

39. 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
A start relay
An uninsulated suction line and a restricted metering device

40. 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
It is used to control refrigerant pressure in the compressor crankcase
Technician A
The low-side pressure will decrease and the evaporator coil will be partially frosted
Always have some liquid present in the bulb and diaphragm

41. 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 start relay
The external equalizer could be plugged
An overcharged system
Flooding the condenser - cycling condenser fans - and dampering condenser air

42. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
110-120
An acid-core suction line drier
The superheat increases and the subcooling decreases
Technician B

43. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Run with high head and high suction pressure
Low superheat
A blown fuse
The system has been overcharged+The system has air trapped in the condenser

44. 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
Technician B
Whenever necessary
Bad compressor valve

45. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
Low discharge pressure - high suction pressure - and low amp draw
Evaporator and compressor
Current in the compressor circuit

46. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
A start relay
Low superheat

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

48. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Increases starting torque

49. 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
('Y' and 'C') and ('G' and 'C')
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure

50. 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
The superheat increases and the subcooling decreases
An overcharged system
Technician B