Test your basic knowledge |

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. 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 system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Increases starting torque
Flooding the condenser - cycling condenser fans - and dampering condenser air
The internal overload is opened

2. What are the symptoms of an air conditioning system that has a low charge...
Flooding the condenser - cycling condenser fans - and dampering condenser air
The low-side pressure will decrease and the evaporator coil will be partially frosted
A start capacitor and a solid-state relay
The superheat increases and the subcooling decreases

3. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
A blown fuse
110-120
An increase in suction pressure and an increase in discharge pressure
A low refrigerant charge

4. 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 internal overload is opened
A sensing bulb improperly connected to the suction line
A start relay
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

5. Technician A says that to manually pump down an air conditioning system with a two-position service valve - the liquid line must be front-seated and the high- and low-side pressure will decrease to 0 psig when the pump-down is complete. Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
High superheat and low discharge pressure
It would cause the low-side pressure to decrease
Technician A is correct

6. 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
The external equalizer could be plugged
It keeps a constant superheat in the evaporator
An undercharge and low ambient conditions
A missing air filter+improper rotation of the indoor blower+blower too small

7. A compressor having tight bearings would cause the current value to...
Low discharge pressure - high suction pressure - and low amp draw
It is used to control refrigerant pressure in the compressor crankcase
The oil pump pressure and the crankcase pressure
Rise more than normal

8. 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
A start capacitor and a solid-state relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Current in the compressor circuit

9. What problem or problems can cause low discharge and suction pressure...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The oil pump pressure and the crankcase pressure
An undercharged system+insufficient airflow over the evaporator coil
A sensing bulb improperly connected to the suction line

10. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician B
An increase in suction pressure and an increase in discharge pressure
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Dirty condenser - bent condenser fins - and air recirculating over the condenser

11. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
Partially frosted evaporator and high superheat
Both technicians are incorrect
It would cause the low-side pressure to decrease
Evaporator and compressor

12. A hard-start kit for an air conditioning system...
Increases starting torque
50-65
Technician B
Current in the compressor circuit

13. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The sight glass is full of liquid+the sight glass is full of gas
Technician A
An undercharge and low ambient conditions

14. 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
Current in the compressor circuit
'G' to 'C'
An uninsulated suction line and a restricted metering device

15. What is the purpose of an EPR valve...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Increases starting torque
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
It keeps a constant superheat in the evaporator

16. 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 uninsulated suction line and a restricted metering device
Broken rings+broken valves+seized bearings
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

17. 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
An undercharge and low ambient conditions
The oil pump pressure and the crankcase pressure
50-65

18. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Technician B
20 to 30
Evaporator and compressor
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

19. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
20 to 30
A low refrigerant charge
Increases starting torque
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

20. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A missing air filter+improper rotation of the indoor blower+blower too small
Always have some liquid present in the bulb and diaphragm
An increase in suction pressure and an increase in discharge pressure

21. A technician arrives on the job and the customer complains that there is no cooling on his rooftop unit. Troubleshooting the system - the technician finds that the compressor is faulty. He notices that there is another faulty compressor laying next t
'G' to 'C'
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Always have some liquid present in the bulb and diaphragm
Broken rings+broken valves+seized bearings

22. What are two common symptoms of refrigerant leaks in an air conditioning system...
The external equalizer could be plugged
Short cycling and insufficient dehumidification
A plugged filter drier
Partially frosted evaporator and high superheat

23. Why is it unsafe to operate an air conditioning system with a low charge...
A start capacitor and a solid-state relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Increases starting torque
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

24. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Evaporator and compressor
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Low voltage and a faulty start relay

25. Which of the following is a common cause of an excessively low superheat on a TXV system...
The internal overload is opened
A sensing bulb improperly connected to the suction line
A vacuum test+oil traces around fittings+soap bubble solution
Technician B

26. Which of the following will cause excessive discharge pressures on an air conditioning system...
Always have some liquid present in the bulb and diaphragm
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Evaporator and compressor
It keeps a constant superheat in the evaporator

27. Insufficient airflow can be caused by...
A start relay
An increase of air leakage from ductwork
Run with high head and high suction pressure
The oil pump pressure and the crankcase pressure

28. When using a vapor-charged TXV bulb - it is necessary to have...
20 to 30
Technician B
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The sensing bulb at a lower temperature than the valve body

29. What are two common symptoms of refrigerant leaks in an air conditioning system...
An increase in low-side pressure
A sensing bulb improperly connected to the suction line
Partially frosted evaporator and high superheat
A defective circuit breaker

30. A hard-start kit consists of...
Low superheat
A blown fuse
A start capacitor and a solid-state relay
The external equalizer could be plugged

31. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
A plugged filter drier
Low discharge pressure - high suction pressure - and low amp draw
Technician B
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

32. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Low discharge pressure - high suction pressure - and low amp draw
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

33. A customer calls with an insufficient cooling complaint on a 90
Technician B
Broken rings+broken valves+seized bearings
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It would cause the low-side pressure to decrease

34. 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...
Low superheat
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted

35. 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...

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183

36. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Short cycling and insufficient dehumidification
20 to 30
3 psig
Low discharge pressure - high suction pressure - and low amp draw

37. 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
Technician A
Both technicians are incorrect
Run with high head and high suction pressure

38. What are three methods for controlling a system's high-side pressure during low ambient conditions...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Evaporator and compressor
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B

39. What type of problems can be caused by an oversized air conditioning system...
A vacuum test+oil traces around fittings+soap bubble solution
Short cycling and insufficient dehumidification
The system has been overcharged+The system has air trapped in the condenser
A vacuum test+oil traces around fittings+soap bubble solution

40. Which of the following is a common cause of an excessively low superheat on a TXV system...
Both technicians are correct
Flooding the condenser - cycling condenser fans - and dampering condenser air
A restricted metering device
A sensing bulb improperly connected to the suction line

41. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
High superheat and low discharge pressure
Clean the condenser coil
It keeps a constant superheat in the evaporator
An acid-core suction line drier

42. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
Technician A
Increases starting torque
Technician B
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

43. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
110-120
The discharge pressure increases and the amperage increases
The superheat increases and the subcooling decreases
An uninsulated suction line and a restricted metering device

44. Which of the following can cause excessive subcooling...
An overcharged system
A missing air filter+improper rotation of the indoor blower+blower too small
An acid-core suction line drier
Technician B

45. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Technician B
An acid-core suction line drier
Condenser fans operating during a low ambient condition and a low suction pressure

46. 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
Condenser fans operating during a low ambient condition and a low suction pressure
An open internal overload protector
Condenser fans operating during a low ambient condition and a low suction pressure

47. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Technician B
It is used to control refrigerant pressure in the compressor crankcase
The external equalizer could be plugged
The superheat increases and the subcooling decreases

48. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
'G' to 'C'
A missing air filter+improper rotation of the indoor blower+blower too small
3 psig

49. Which of the following could be the cause for a system's discharge and suction pressure being low...
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A restricted metering device
The superheat will increase and the low-side pressure will decrease
The sensing bulb at a lower temperature than the valve body

50. What are two problems that can cause an air conditioning system to have an excessively high superheat...
3 psig
A start capacitor and a solid-state relay
An uninsulated suction line and a restricted metering device
Lack of airflow