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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 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 discharge pressure increases and the amperage increases
Both technicians are incorrect
Technician B
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

2. 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...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
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
Flooding the condenser - cycling condenser fans - and dampering condenser air

3. Which of the following can cause excessive subcooling...
A bad thermostat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An acid-core suction line drier
An overcharged system

4. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It would cause the low-side pressure to decrease
Technician B
The internal overload is opened
A vacuum test+oil traces around fittings+soap bubble solution

5. Air filters should be replaced...
Both technicians are correct
Whenever necessary
An increase of air leakage from ductwork
Bad compressor valve

6. A hard-start kit for an air conditioning system...
Whenever necessary
Increases starting torque
The oil pump pressure and the crankcase pressure
Evaporator and compressor

7. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase in suction pressure and an increase in discharge pressure
The discharge pressure increases and the amperage increases

8. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A low refrigerant charge
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The superheat will increase and the low-side pressure will decrease

9. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Always have some liquid present in the bulb and diaphragm
Rise more than normal

10. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
High superheat and low discharge pressure
A vacuum test+oil traces around fittings+soap bubble solution
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

11. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low voltage and a faulty start relay
The system has been overcharged+The system has air trapped in the condenser
Technician B

12. A system that is operating with a clear sight glass shows...
An uninsulated suction line and a restricted metering device
Increases starting torque
The sight glass is full of liquid+the sight glass is full of gas
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

13. What is the common cause of a compressor burnout...
Increases starting torque
'G' to 'C'
50-65
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

14. 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...
A sensing bulb improperly connected to the suction line
3 psig
The internal overload is opened
An increase of air leakage from ductwork

15. What are three methods for controlling a system's high-side pressure during low ambient conditions...
A vacuum test+oil traces around fittings+soap bubble solution
A missing air filter+improper rotation of the indoor blower+blower too small
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air

16. 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
Both technicians are incorrect
Broken rings+broken valves+seized bearings
The discharge pressure increases and the amperage increases
Partially frosted evaporator and high superheat

17. 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
Both technicians are incorrect
An increase in suction pressure and an increase in discharge pressure
Rise more than normal
A bad thermostat

18. 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
Technician B
A bad thermostat
A low refrigerant charge
Low voltage and a faulty start relay

19. A hard-start kit consists of...
A start capacitor and a solid-state relay
Run with high head and high suction pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A restricted metering device

20. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Condenser fans operating during a low ambient condition and a low suction pressure
The oil pump pressure and the crankcase pressure
Run with high head and high suction pressure
Low superheat

21. Which of the following can cause low superheat in a TXV system...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An uninsulated TXV sensing bulb
An overcharged system
Technician B

22. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Current in the compressor circuit
The external equalizer could be plugged

23. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician A is correct
A plugged filter drier
Bad compressor valve
The low-side pressure will decrease and the evaporator coil will be partially frosted

24. 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 defective circuit breaker
An overcharged system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The external equalizer could be plugged

25. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
An overcharged system
The superheat will increase and the low-side pressure will decrease
Partially frosted evaporator and high superheat
Run with high head and high suction pressure

26. What are common methods that are used for leak-testing a system...
Technician B
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A vacuum test+oil traces around fittings+soap bubble solution

27. 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
Partially frosted evaporator and high superheat
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician B
Both technicians are correct

28. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
An acid-core suction line drier
110-120
Technician B
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

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...
Technician B
A blown fuse
The superheat will increase and the low-side pressure will decrease
Technician B

30. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
An undercharge and low ambient conditions
Broken rings+broken valves+seized bearings
The sight glass is full of liquid+the sight glass is full of gas
An acid-core suction line drier

31. 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...
An increase in low-side pressure
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
110-120

32. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A
A plugged filter drier
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

33. 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
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Contains a solenoid coil and one or more sets of contacts
Technician B
Increases starting torque

34. A hard-start kit for an air conditioning system...
Technician B
An overcharged system
Increases starting torque
High suction pressure and low superheat

35. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician B
A blown fuse
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

36. The temperature range of the suction line from an air conditioning system should be...
50-65
Technician B
An increase in low-side pressure
Broken rings+broken valves+seized bearings

37. 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
A missing air filter+improper rotation of the indoor blower+blower too small
An uninsulated TXV sensing bulb
Dirty condenser - bent condenser fins - and air recirculating over the condenser

38. What are the operating pressures of an oil pressure safety switch...
Evaporator and compressor
It is used to control refrigerant pressure in the compressor crankcase
The oil pump pressure and the crankcase pressure
The system has been overcharged+The system has air trapped in the condenser

39. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
An acid-core suction line drier
Bad compressor valve
Both technicians are correct

40. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
20 to 30
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
110-120
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

41. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Clean the condenser coil
Current in the compressor circuit
Lack of airflow
Evaporator and compressor

42. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
An increase in suction pressure and an increase in discharge pressure
A blown fuse
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air

43. A system that uses a thermal electric expansion valve...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The internal overload is opened
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

44. Which of the following is a common cause of an excessively low superheat on a TXV system...
An acid-core suction line drier
A sensing bulb improperly connected to the suction line
Always have some liquid present in the bulb and diaphragm
'G' to 'C'

45. What is the purpose of an EPR valve...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A restricted metering device
An overcharged system
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

46. 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
Always have some liquid present in the bulb and diaphragm
Both technicians are incorrect
Technician B
'G' to 'C'

47. What is the common cause of a compressor burnout...
An undercharge and low ambient conditions
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

48. 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
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
Technician A

49. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Bad compressor valve
Contains a solenoid coil and one or more sets of contacts
An undercharge and low ambient conditions
Broken rings+broken valves+seized bearings

50. 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
20 to 30
50-65
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system