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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. 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
A sensing bulb improperly connected to the suction line
Technician B
The superheat increases and the subcooling decreases

2. A system that is operating with a clear sight glass shows...
Partially frosted evaporator and high superheat
The sight glass is full of liquid+the sight glass is full of gas
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Current in the compressor circuit

3. 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 superheat will increase and the low-side pressure will decrease
A low refrigerant charge
A start relay
Technician B

4. A hard-start kit consists of...
Flooding the condenser - cycling condenser fans - and dampering condenser air
50-65
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A start capacitor and a solid-state relay

5. What type of problems can be caused by an oversized air conditioning system...
An undercharged system+insufficient airflow over the evaporator coil
Low voltage and a faulty start relay
Short cycling and insufficient dehumidification
Evaporator and compressor

6. 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...
Increases starting torque
The internal overload is opened
Flooding the condenser - cycling condenser fans - and dampering condenser air
Technician B

7. 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
An overcharged system
A bad thermostat
A restricted metering device

8. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Both technicians are incorrect
Technician B

9. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It is used to control refrigerant pressure in the compressor crankcase
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

10. A hard-start kit for an air conditioning system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Lack of airflow
Increases starting torque
Current in the compressor circuit

11. Which of the following can cause low superheat in a TXV system...
It keeps a constant superheat in the evaporator
Both technicians are correct
Both technicians are incorrect
An uninsulated TXV sensing bulb

12. 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
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Clean the condenser coil
A bad thermostat

13. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
The superheat will increase and the low-side pressure will decrease
Technician A
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Broken rings+broken valves+seized bearings

14. A compressor having tight bearings would cause the current value to...
Low voltage and a faulty start relay
An undercharged system+insufficient airflow over the evaporator coil
Technician B
Rise more than normal

15. 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
An undercharge and low ambient conditions
An acid-core suction line drier
The superheat will increase and the low-side pressure will decrease

16. What is the purpose of a CPR valve...
It is used to control refrigerant pressure in the compressor crankcase
Rise more than normal
Always have some liquid present in the bulb and diaphragm
Technician B

17. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Technician B
The oil pump pressure and the crankcase pressure
An overcharged system
The low-side pressure will decrease and the evaporator coil will be partially frosted

18. 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
An undercharge and low ambient conditions
The discharge pressure increases and the amperage increases
Technician B
An uninsulated suction line and a restricted metering device

19. 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
An increase of air leakage from ductwork
Technician B
Technician B
A defective circuit breaker

20. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
The superheat will increase and the low-side pressure will decrease
Both technicians are incorrect
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

21. 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
Technician B
An increase in low-side pressure
A start capacitor and a solid-state relay

22. A customer calls with an insufficient cooling complaint on a 90
A blown fuse
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A start relay
Technician B

23. 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
The oil pump pressure and the crankcase pressure
A plugged filter drier
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Technician A

24. Insufficient airflow can be caused by...
'G' to 'C'
The sight glass is full of liquid+the sight glass is full of gas
An increase of air leakage from ductwork
The sensing bulb at a lower temperature than the valve body

25. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A bad thermostat
A missing air filter+improper rotation of the indoor blower+blower too small
The superheat increases and the subcooling decreases
The discharge pressure increases and the amperage increases

26. A hard-start kit consists of...
A vacuum test+oil traces around fittings+soap bubble solution
Technician A
Increases starting torque
A start capacitor and a solid-state relay

27. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Bad compressor valve
High suction pressure and low superheat

28. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
An increase of air leakage from ductwork
Broken rings+broken valves+seized bearings
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An uninsulated suction line and a restricted metering device

29. A system that uses a thermal electric expansion valve...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

30. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Technician B
'G' to 'C'
It would cause the low-side pressure to decrease
Lack of airflow

31. A liquid-charged TXV bulb will...
50-65
The superheat increases and the subcooling decreases
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Always have some liquid present in the bulb and diaphragm

32. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Low discharge pressure - high suction pressure - and low amp draw
An increase in suction pressure and an increase in discharge pressure
Always have some liquid present in the bulb and diaphragm
Broken rings+broken valves+seized bearings

33. 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
High suction pressure and low superheat
A bad thermostat
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

34. Air filters should be replaced...
Whenever necessary
The discharge pressure increases and the amperage increases
A vacuum test+oil traces around fittings+soap bubble solution
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure

35. 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
('Y' and 'C') and ('G' and 'C')
Evaporator and compressor
The system has been overcharged+The system has air trapped in the condenser

36. What is the purpose of an EPR valve...
Both technicians are incorrect
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
('Y' and 'C') and ('G' and 'C')
An uninsulated suction line and a restricted metering device

37. 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...
The superheat increases and the subcooling decreases
Lack of airflow
It keeps a constant superheat in the evaporator
High superheat and low discharge pressure

38. 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
'G' to 'C'
Technician B
The superheat increases and the subcooling decreases
High suction pressure and low superheat

39. The best description of a relay would be...
Increases starting torque
Contains a solenoid coil and one or more sets of contacts
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

40. 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
A bad thermostat
Low discharge pressure - high suction pressure - and low amp draw
Technician B
Clean the condenser coil

41. What causes the automatic expansion valve to close...
Technician A is correct
Contains a solenoid coil and one or more sets of contacts
An increase in low-side pressure
Condenser fans operating during a low ambient condition and a low suction pressure

42. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Increases starting torque
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A defective circuit breaker

43. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
A plugged filter drier
An overcharged system
High superheat and low discharge pressure

44. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
It is used to control refrigerant pressure in the compressor crankcase
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
It keeps a constant superheat in the evaporator
It would cause the low-side pressure to decrease

45. What problem or problems can cause low discharge and suction pressure...
Technician A is correct
Technician B
An undercharged system+insufficient airflow over the evaporator coil
An uninsulated suction line and a restricted metering device

46. Which of the following will cause excessive discharge pressures on an air conditioning system...
Rise more than normal
A plugged filter drier
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system

47. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
High suction pressure and low superheat
Technician B
An overcharged system
It would cause the low-side pressure to decrease

48. 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

49. Which of the following will cause excessive discharge pressures on an air conditioning system...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
50-65
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated TXV sensing bulb

50. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
('Y' and 'C') and ('G' and 'C')
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
An overcharged system
Always have some liquid present in the bulb and diaphragm