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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 common methods that are used for leak-testing a system...
The discharge pressure increases and the amperage increases
A defective circuit breaker
A vacuum test+oil traces around fittings+soap bubble solution
Short cycling and insufficient dehumidification

2. 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
Both technicians are correct
A start capacitor and a solid-state relay
20 to 30

3. 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
An overcharged system
A blown fuse
The low-side pressure will decrease and the evaporator coil will be partially frosted

4. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
It keeps a constant superheat in the evaporator
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start relay
The sensing bulb at a lower temperature than the valve body

5. The best description of a relay would be...
A plugged filter drier
Contains a solenoid coil and one or more sets of contacts
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The low-side pressure will decrease and the evaporator coil will be partially frosted

6. A restricted air filter in an air conditioning system can be identified by...
Low superheat
'G' to 'C'
A plugged filter drier
Current in the compressor circuit

7. Superheat is found in an air conditioning system in the...
The sight glass is full of liquid+the sight glass is full of gas
Evaporator and compressor
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B

8. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
110-120
Rise more than normal
An undercharge and low ambient conditions
A plugged filter drier

9. 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
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
It would cause the low-side pressure to decrease
A vacuum test+oil traces around fittings+soap bubble solution

10. A system that uses a thermal electric expansion valve...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The sight glass is full of liquid+the sight glass is full of gas
Rise more than normal
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

11. Insufficient airflow can be caused by...
Always have some liquid present in the bulb and diaphragm
An increase of air leakage from ductwork
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

12. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A plugged filter drier
An increase of air leakage from ductwork
High suction pressure and low superheat

13. 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
Broken rings+broken valves+seized bearings
A vacuum test+oil traces around fittings+soap bubble solution
An increase in low-side pressure
A restricted metering device

14. 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
Run with high head and high suction pressure
Low voltage and a faulty start relay
Technician B
A start capacitor and a solid-state relay

15. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
A bad thermostat
An open internal overload protector
The discharge pressure increases and the amperage increases
20 to 30

16. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
A blown fuse
Both technicians are correct

17. What are two common problems that can cause a sight glass in an air conditioning to have bubbles...
('Y' and 'C') and ('G' and 'C')
An uninsulated TXV sensing bulb
An undercharge and low ambient conditions
A start capacitor and a solid-state relay

18. The best description of a relay would be...
Low voltage and a faulty start relay
Contains a solenoid coil and one or more sets of contacts
A defective circuit breaker
Flooding the condenser - cycling condenser fans - and dampering condenser air

19. A liquid-charged TXV bulb will...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Technician B
The low-side pressure will decrease and the evaporator coil will be partially frosted
Always have some liquid present in the bulb and diaphragm

20. Which of the following can cause excessive subcooling...
Run with high head and high suction pressure
An overcharged system
Technician A is correct
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

21. 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
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An overcharged system
Technician B
It is used to control refrigerant pressure in the compressor crankcase

22. A customer calls to complain that his central air conditioning system is not cooling properly. The technician arrives on the job. He or she notices that the indoor blower has adequate airflow and the outdoor condenser fan is operating - but the compr
Partially frosted evaporator and high superheat
The superheat increases and the subcooling decreases
Clean the condenser coil
An open internal overload protector

23. 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...
A vacuum test+oil traces around fittings+soap bubble solution
A blown fuse
A bad thermostat
A start relay

24. A hard-start kit consists of...
A start capacitor and a solid-state relay
An undercharge and low ambient conditions
Always have some liquid present in the bulb and diaphragm
Bad compressor valve

25. 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
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Partially frosted evaporator and high superheat
An overcharged system

26. A system that is operating with a clear sight glass shows...
A start relay
The sight glass is full of liquid+the sight glass is full of gas
Technician B
The superheat will increase and the low-side pressure will decrease

27. An air conditioning system using a fixed-orifice metering device and with noncondensables in the system will cause...
It would cause the low-side pressure to decrease
Flooding the condenser - cycling condenser fans - and dampering condenser air
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Run with high head and high suction pressure

28. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A sensing bulb improperly connected to the suction line
A defective circuit breaker
An increase in low-side pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan

29. What are the symptoms of a TXV air conditioning system if it has lost its charge...
An undercharge and low ambient conditions
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The superheat will increase and the low-side pressure will decrease
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

30. 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
An undercharge and low ambient conditions
An acid-core suction line drier
The discharge pressure increases and the amperage increases

31. What is the purpose of an EPR valve...
Bad compressor valve
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
An increase in suction pressure and an increase in discharge pressure
Technician B

32. 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
Short cycling and insufficient dehumidification
Increases starting torque
Technician B

33. 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
The superheat will increase and the low-side pressure will decrease
A missing air filter+improper rotation of the indoor blower+blower too small
The internal overload is opened

34. Which of the following can cause low superheat in a TXV system...
An increase of air leakage from ductwork
An uninsulated TXV sensing bulb
Both technicians are incorrect
A plugged filter drier

35. A commercial customer calls on a 90
The oil pump pressure and the crankcase pressure
High suction pressure and low superheat
A defective circuit breaker
The system has been overcharged+The system has air trapped in the condenser

36. What is the purpose of the TXV...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Run with high head and high suction pressure
It keeps a constant superheat in the evaporator
Technician B

37. 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
Low discharge pressure - high suction pressure - and low amp draw
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B

38. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
Broken rings+broken valves+seized bearings
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
High superheat and low discharge pressure

39. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A vacuum test+oil traces around fittings+soap bubble solution
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A dirty condenser - recirculation of condenser air - and a defective condenser fan
A plugged filter drier

40. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The superheat increases and the subcooling decreases
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low superheat

41. Insufficient airflow can be caused by...
An increase of air leakage from ductwork
Increases starting torque
The superheat will increase and the low-side pressure will decrease
Short cycling and insufficient dehumidification

42. What is the common cause of a compressor burnout...
An uninsulated TXV sensing bulb
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
('Y' and 'C') and ('G' and 'C')
The discharge pressure increases and the amperage increases

43. What are the symptoms of an air conditioning system that has a low charge...
Contains a solenoid coil and one or more sets of contacts
'G' to 'C'
The low-side pressure will decrease and the evaporator coil will be partially frosted
Current in the compressor circuit

44. 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

45. 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
An increase of air leakage from ductwork
An uninsulated TXV sensing bulb
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
The system has been overcharged+The system has air trapped in the condenser

46. 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
Low superheat
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician A
A bad thermostat

47. Which of the following can cause excessive subcooling...
An overcharged system
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
The system has been overcharged+The system has air trapped in the condenser

48. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
A plugged filter drier
An increase in suction pressure and an increase in discharge pressure
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Lack of airflow

49. 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
An overcharged system
A defective circuit breaker
The sight glass is full of liquid+the sight glass is full of gas
Clean the condenser coil

50. 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
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
Whenever necessary
An overcharged system