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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. 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
The sight glass is full of liquid+the sight glass is full of gas
A start relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan

2. Air filters should be replaced...
Whenever necessary
A sensing bulb improperly connected to the suction line
A defective circuit breaker
A sensing bulb improperly connected to the suction line

3. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An overcharged system
Technician A
A restricted metering device

4. 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 acid-core suction line drier
Low discharge pressure - high suction pressure - and low amp draw
An uninsulated suction line and a restricted metering device
Technician B

5. 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
A sensing bulb improperly connected to the suction line
The superheat increases and the subcooling decreases
Technician B
An undercharged system+insufficient airflow over the evaporator coil

6. When using a vapor-charged TXV bulb - it is necessary to have...
A start relay
Both technicians are incorrect
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The sensing bulb at a lower temperature than the valve body

7. 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
An increase in suction pressure and an increase in discharge pressure
Technician B
A defective circuit breaker

8. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Current in the compressor circuit
Lack of airflow
A low refrigerant charge

9. Insufficient airflow can be caused by...
An increase in low-side pressure
Technician B
An increase of air leakage from ductwork
Both technicians are correct

10. What causes the automatic expansion valve to close...
An increase in low-side pressure
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
The sensing bulb at a lower temperature than the valve body
High suction pressure and low superheat

11. 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
110-120
An increase in low-side pressure
Clean the condenser coil
Evaporator and compressor

12. A customer calls with an insufficient cooling complaint on a 90
3 psig
Technician B
It keeps a constant superheat in the evaporator
An increase of air leakage from ductwork

13. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Low voltage and a faulty start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted

14. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The oil pump pressure and the crankcase pressure
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A is correct
Technician B

15. What problem can cause an increase of discharge pressure and an increase of suction pressure...
An overcharged system
Technician B
3 psig
Technician B

16. What are two problems that can cause an air conditioning system to have an excessively high superheat...
An acid-core suction line drier
An uninsulated suction line and a restricted metering device
Technician B
Broken rings+broken valves+seized bearings

17. 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
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A sensing bulb improperly connected to the suction line
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

18. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A missing air filter+improper rotation of the indoor blower+blower too small
Bad compressor valve
It keeps a constant superheat in the evaporator

19. The temperature range of the suction line from an air conditioning system should be...
Broken rings+broken valves+seized bearings
50-65
An increase in suction pressure and an increase in discharge pressure
Rise more than normal

20. What are the symptoms of a TXV air conditioning system if it has lost its charge...
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An overcharged system
The superheat will increase and the low-side pressure will decrease

21. What are two common symptoms of refrigerant leaks in an air conditioning system...
Technician B
Technician A
Partially frosted evaporator and high superheat
An overcharged system

22. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
Bad compressor valve
High suction pressure and low superheat
50-65
A restricted metering device

23. 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
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
Current in the compressor circuit
A defective circuit breaker

24. What is the purpose of a CPR valve...
Low voltage and a faulty start relay
It is used to control refrigerant pressure in the compressor crankcase
Condenser fans operating during a low ambient condition and a low suction pressure
('Y' and 'C') and ('G' and 'C')

25. What type of problems can be caused by an oversized air conditioning system...
('Y' and 'C') and ('G' and 'C')
The system has been overcharged+The system has air trapped in the condenser
50-65
Short cycling and insufficient dehumidification

26. What are common methods that are used for leak-testing a system...
Increases starting torque
Bad compressor valve
A defective circuit breaker
A vacuum test+oil traces around fittings+soap bubble solution

27. Which of the following could be the cause for a system's discharge and suction pressure being low...
An increase of air leakage from ductwork
The superheat increases and the subcooling decreases
A restricted metering device
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

28. A liquid-charged TXV bulb will...
An undercharge and low ambient conditions
The low-side pressure will decrease and the evaporator coil will be partially frosted
Always have some liquid present in the bulb and diaphragm
Technician B

29. 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
Increases starting torque
Partially frosted evaporator and high superheat
The discharge pressure increases and the amperage increases
Technician B

30. 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
Both technicians are incorrect
The external equalizer could be plugged
The superheat will increase and the low-side pressure will decrease

31. 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
Contains a solenoid coil and one or more sets of contacts
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Always have some liquid present in the bulb and diaphragm

32. A hard-start kit consists of...
Technician B
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B
A start capacitor and a solid-state relay

33. A compressor having tight bearings would cause the current value to...
Increases starting torque
An undercharge and low ambient conditions
Rise more than normal
An overcharged system

34. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
The superheat increases and the subcooling decreases
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An uninsulated TXV sensing bulb

35. Insufficient airflow can be caused by...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
An acid-core suction line drier
An increase of air leakage from ductwork
Run with high head and high suction pressure

36. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Technician B
Low superheat
Whenever necessary
Dirty condenser - bent condenser fins - and air recirculating over the condenser

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
Whenever necessary
The oil pump pressure and the crankcase pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

38. 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
It would cause the low-side pressure to decrease
Technician A
The superheat will increase and the low-side pressure will decrease
Technician B

39. What three things can prevent an air conditioning system from releasing heat at the proper rate...
Contains a solenoid coil and one or more sets of contacts
A defective circuit breaker
A dirty condenser - recirculation of condenser air - and a defective condenser fan
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system

40. 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
A start capacitor and a solid-state relay
Technician B
Technician A

41. Which of the following is a possible cause for a compressor to overheat...
A low refrigerant charge
Always have some liquid present in the bulb and diaphragm
Technician A is correct
A defective circuit breaker

42. 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
Current in the compressor circuit
The external equalizer could be plugged
A plugged filter drier
Rise more than normal

43. What causes the automatic expansion valve to close...
An increase in low-side pressure
Partially frosted evaporator and high superheat
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect

44. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
Current in the compressor circuit
Both technicians are correct
A start capacitor and a solid-state relay
Run with high head and high suction pressure

45. Why is it unsafe to operate an air conditioning system with a low charge...
Short cycling and insufficient dehumidification
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Both technicians are incorrect
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

46. A commercial customer calls complaining that her rooftop air conditioning system is not operating. The technician arrives on the job and sets the thermostat to cooling - then notices that the indoor fan is not operating. The technician then sets the

47. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician A
High superheat and low discharge pressure

48. Which of the following can cause low superheat in a TXV system...
An uninsulated TXV sensing bulb
Whenever necessary
The sight glass is full of liquid+the sight glass is full of gas
Flooding the condenser - cycling condenser fans - and dampering condenser air

49. Which of the following will cause excessive discharge pressures on an air conditioning system...
The external equalizer could be plugged
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect

50. Which of the following could be the cause for a system's discharge and suction pressure being low...
A plugged filter drier
Technician A is correct
The oil pump pressure and the crankcase pressure
A restricted metering device