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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. 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
A sensing bulb improperly connected to the suction line
Technician B
An undercharge and low ambient conditions
An overcharged system

2. 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
An uninsulated suction line and a restricted metering device
A low refrigerant charge
An increase of air leakage from ductwork

3. Which of the following is a possible cause for a compressor to overheat...
Technician A is correct
A low refrigerant charge
A start relay
Partially frosted evaporator and high superheat

4. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Lack of airflow
Current in the compressor circuit
Low discharge pressure - high suction pressure - and low amp draw
Dirty condenser - bent condenser fins - and air recirculating over the condenser

5. What types of symptoms will be present if the sensing bulb of a TXV is not properly connected...
50-65
Rise more than normal
An increase of air leakage from ductwork
High suction pressure and low superheat

6. 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 internal overload is opened
An undercharge and low ambient conditions
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

7. What is the common cause of a compressor burnout...
Technician A is correct
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An open internal overload protector
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser

8. After a compressor motor has been severely burnt - What accessory must be added as an aid to rid the air conditioning system of acid...
Increases starting torque
An acid-core suction line drier
It would cause the low-side pressure to decrease
The internal overload is opened

9. Insufficient airflow can be caused by...
Run with high head and high suction pressure
An open internal overload protector
An increase of air leakage from ductwork
Both technicians are correct

10. 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 undercharge and low ambient conditions
Clean the condenser coil
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Technician B

11. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A low refrigerant charge
The discharge pressure increases and the amperage increases
Technician A
110-120

12. The technician observes a pressure drop of 25 degrees across an air conditioning evaporator coil at start-up. This drop would indicate...
Lack of airflow
High suction pressure and low superheat
The sight glass is full of liquid+the sight glass is full of gas
Dirty condenser - bent condenser fins - and air recirculating over the condenser

13. 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
An increase in low-side pressure
The external equalizer could be plugged
It would cause the low-side pressure to decrease

14. A restricted air filter in an air conditioning system can be identified by...
Low superheat
A sensing bulb improperly connected to the suction line
A vacuum test+oil traces around fittings+soap bubble solution
Technician A

15. A customer calls with an insufficient cooling complaint on a 90
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
An undercharge and low ambient conditions
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B

16. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
It would cause the low-side pressure to decrease
A missing air filter+improper rotation of the indoor blower+blower too small
An overcharged system
Technician B

17. What is the purpose of the TXV...
An increase of air leakage from ductwork
Both technicians are incorrect
It keeps a constant superheat in the evaporator
Technician B

18. 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
Current in the compressor circuit
A restricted metering device
Evaporator and compressor

19. What three things can prevent an air conditioning system from releasing heat at the proper rate...
A plugged filter drier
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
A dirty condenser - recirculation of condenser air - and a defective condenser fan
Technician B

20. A system that uses a thermal electric expansion valve...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Technician B
It would cause the low-side pressure to decrease
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system

21. The internal overload of an air conditioning compressor senses winding temperature and...
Current in the compressor circuit
An open internal overload protector
Condenser fans operating during a low ambient condition and a low suction pressure
High superheat and low discharge pressure

22. What are the symptoms of an air conditioning system that has a low charge...
Low superheat
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
Low voltage and a faulty start relay

23. 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
High suction pressure and low superheat
Broken rings+broken valves+seized bearings
Technician B
An undercharge and low ambient conditions

24. A commercial customer calls on a 90
The system has been overcharged+The system has air trapped in the condenser
Whenever necessary
Low voltage and a faulty start relay
Partially frosted evaporator and high superheat

25. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
Technician B
An uninsulated suction line and a restricted metering device
Dirty condenser - bent condenser fins - and air recirculating over the condenser

26. Which of the following will cause excessive discharge pressures on an air conditioning system...
Flooding the condenser - cycling condenser fans - and dampering condenser air
Lack of airflow
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Dirty condenser - bent condenser fins - and air recirculating over the condenser

27. A liquid-charged TXV bulb will...
Technician B
A low refrigerant charge
Short cycling and insufficient dehumidification
Always have some liquid present in the bulb and diaphragm

28. 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
Condenser fans operating during a low ambient condition and a low suction pressure
Both technicians are incorrect
An increase of air leakage from ductwork

29. 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
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The internal overload is opened

30. 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
Technician A is correct
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Broken rings+broken valves+seized bearings

31. 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...
High superheat and low discharge pressure
20 to 30
A sensing bulb improperly connected to the suction line
The discharge pressure increases and the amperage increases

32. 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
('Y' and 'C') and ('G' and 'C')
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

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
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
It keeps a constant superheat in the evaporator
A bad thermostat
Technician B

34. 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
Current in the compressor circuit
High suction pressure and low superheat
Technician A is correct
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay

35. Which of the following can cause low superheat in a TXV system...
An uninsulated suction line and a restricted metering device
An uninsulated TXV sensing bulb
Technician B
50-65

36. 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
High suction pressure and low superheat
Technician B
An overcharged system
('Y' and 'C') and ('G' and 'C')

37. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
110-120
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
A start capacitor and a solid-state relay

38. Which of the following could be the cause for a system's discharge and suction pressure being low...
The sensing bulb at a lower temperature than the valve body
110-120
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A restricted metering device

39. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Contains a solenoid coil and one or more sets of contacts
Partially frosted evaporator and high superheat
Technician B

40. Which of the following is a possible cause for a compressor to overheat...
Both technicians are incorrect
The low-side pressure will decrease and the evaporator coil will be partially frosted
Always have some liquid present in the bulb and diaphragm
A low refrigerant charge

41. What are two common symptoms of refrigerant leaks in an air conditioning system...
Technician B
A bad thermostat
Partially frosted evaporator and high superheat
Run with high head and high suction pressure

42. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The superheat will increase and the low-side pressure will decrease
A vacuum test+oil traces around fittings+soap bubble solution
An uninsulated suction line and a restricted metering device
110-120

43. 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
20 to 30
The superheat will increase and the low-side pressure will decrease
It keeps a constant superheat in the evaporator
Technician B

44. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Technician B
Current in the compressor circuit
The superheat increases and the subcooling decreases

45. 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
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A defective circuit breaker
Partially frosted evaporator and high superheat
High superheat and low discharge pressure

46. A restricted air filter in an air conditioning system can be identified by...
A blown fuse
Clean the condenser coil
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Low superheat

47. Air filters should be replaced...
Increases starting torque
Partially frosted evaporator and high superheat
A start capacitor and a solid-state relay
Whenever necessary

48. 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
An undercharged system+insufficient airflow over the evaporator coil
('Y' and 'C') and ('G' and 'C')

49. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The sensing bulb at a lower temperature than the valve body
Partially frosted evaporator and high superheat
Low voltage and a faulty start relay
The superheat increases and the subcooling decreases

50. 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...
It would cause the low-side pressure to decrease
The internal overload is opened
Lack of airflow
It keeps a constant superheat in the evaporator