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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 bad compressor discharge valve...
An overcharged system
Low discharge pressure - high suction pressure - and low amp draw
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
An undercharged system+insufficient airflow over the evaporator coil

2. 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 discharge pressure increases and the amperage increases
The oil pump pressure and the crankcase pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted

3. An air conditioning unit has a suction line that is frosted up to the compressor. What faults could cause this to occur...
A low refrigerant charge
A start relay
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
'G' to 'C'

4. 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
Low superheat
Broken rings+broken valves+seized bearings
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system

5. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The superheat will increase and the low-side pressure will decrease
Low discharge pressure - high suction pressure - and low amp draw
Technician B
It would cause the low-side pressure to decrease

6. 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...
3 psig
3 psig
A blown fuse
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication

7. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The superheat will increase and the low-side pressure will decrease
('Y' and 'C') and ('G' and 'C')
50-65

8. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
Increases starting torque
The discharge pressure increases and the amperage increases
Technician B
Short cycling and insufficient dehumidification

9. 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 low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Increases starting torque
A bad thermostat
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor

10. 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
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An undercharged system+insufficient airflow over the evaporator coil
The oil pump pressure and the crankcase pressure

11. 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 sensing bulb at a lower temperature than the valve body
The superheat will increase and the low-side pressure will decrease
Clean the condenser coil
A defective circuit breaker

12. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Clean the condenser coil
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B

13. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
20 to 30
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air

14. A customer calls with an insufficient cooling complaint on a 90
Bad compressor valve
Always have some liquid present in the bulb and diaphragm
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B

15. Insufficient airflow can be caused by...
The discharge pressure increases and the amperage increases
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
An increase of air leakage from ductwork
Flooding the condenser - cycling condenser fans - and dampering condenser air

16. What are two problems that can cause an air conditioning system to have an excessively high superheat...
The oil pump pressure and the crankcase pressure
Both technicians are incorrect
Technician B
An uninsulated suction line and a restricted metering device

17. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Bad compressor valve
The system has been overcharged+The system has air trapped in the condenser
Partially frosted evaporator and high superheat

18. A commercial customer calls on a 90
An undercharge and low ambient conditions
The system has been overcharged+The system has air trapped in the condenser
Clean the condenser coil
Low discharge pressure - high suction pressure - and low amp draw

19. A compressor having tight bearings would cause the current value to...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The external equalizer could be plugged
A low refrigerant charge
Rise more than normal

20. 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...
The discharge pressure increases and the amperage increases
A blown fuse
Both technicians are incorrect
50-65

21. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
('Y' and 'C') and ('G' and 'C')
Technician A
The superheat increases and the subcooling decreases
Both technicians are incorrect

22. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Technician B
An uninsulated suction line and a restricted metering device
A plugged filter drier
A sensing bulb improperly connected to the suction line

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
An open internal overload protector
50-65
Both technicians are incorrect
Broken rings+broken valves+seized bearings

24. The internal overload of an air conditioning compressor senses winding temperature and...
An overcharged system
Current in the compressor circuit
The sight glass is full of liquid+the sight glass is full of gas
The external equalizer could be plugged

25. What is the common cause of a compressor burnout...
The superheat increases and the subcooling decreases
50-65
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
The oil pump pressure and the crankcase pressure

26. 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 B
50-65
The low-side pressure will decrease and the evaporator coil will be partially frosted

27. 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
Technician B
Technician B
An open internal overload protector
Always have some liquid present in the bulb and diaphragm

28. Insufficient airflow can be caused by...
An overcharged system
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
An increase of air leakage from ductwork

29. A hard-start kit for an air conditioning system...
The system has been overcharged+The system has air trapped in the condenser
Short cycling and insufficient dehumidification
Increases starting torque
High suction pressure and low superheat

30. What is the purpose of an EPR valve...
A low refrigerant charge
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A dirty condenser - recirculation of condenser air - and a defective condenser fan

31. A commercial customer calls on a 90
An undercharge and low ambient conditions
50-65
Condenser fans operating during a low ambient condition and a low suction pressure
The system has been overcharged+The system has air trapped in the condenser

32. What three things can prevent an air conditioning system from releasing heat at the proper rate...
The external equalizer could be plugged
Both technicians are incorrect
A missing air filter+improper rotation of the indoor blower+blower too small
A dirty condenser - recirculation of condenser air - and a defective condenser fan

33. What causes the automatic expansion valve to close...
An increase in low-side pressure
Technician B
A plugged filter drier
Low voltage and a faulty start relay

34. Which of the following can cause excessive subcooling...
It keeps a constant superheat in the evaporator
An overcharged system
Lack of airflow
The sensing bulb at a lower temperature than the valve body

35. Which of the following is a common cause of an excessively low superheat on a TXV system...
A sensing bulb improperly connected to the suction line
High suction pressure and low superheat
Lack of airflow
'G' to 'C'

36. 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...
A restricted metering device
The internal overload is opened
Run with high head and high suction pressure
A missing air filter+improper rotation of the indoor blower+blower too small

37. 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
The system has been overcharged+The system has air trapped in the condenser
It keeps a constant superheat in the evaporator
Low voltage and a faulty start relay

38. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Both technicians are incorrect
Condenser fans operating during a low ambient condition and a low suction pressure
An open internal overload protector
Dirty condenser - bent condenser fins - and air recirculating over the condenser

39. What problem or problems can cause low discharge and suction pressure...
The low-side pressure will decrease and the evaporator coil will be partially frosted
A plugged filter drier
An undercharged system+insufficient airflow over the evaporator coil
Current in the compressor circuit

40. What type of problems can be caused by an oversized air conditioning system...
An undercharge and low ambient conditions
Clean the condenser coil
It is used to control refrigerant pressure in the compressor crankcase
Short cycling and insufficient dehumidification

41. 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
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Evaporator and compressor
The discharge pressure increases and the amperage increases
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged

42. 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
Technician A
The sight glass is full of liquid+the sight glass is full of gas
Low voltage and a faulty start relay

43. When using a vapor-charged TXV bulb - it is necessary to have...
3 psig
The sensing bulb at a lower temperature than the valve body
High suction pressure and low superheat
It is used to control refrigerant pressure in the compressor crankcase

44. What is the common cause of a compressor burnout...
A missing air filter+improper rotation of the indoor blower+blower too small
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Technician A is correct

45. The temperature range of the suction line from an air conditioning system should be...
50-65
Whenever necessary
Contains a solenoid coil and one or more sets of contacts
Contains a solenoid coil and one or more sets of contacts

46. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Always have some liquid present in the bulb and diaphragm
A plugged filter drier
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil

47. A system that uses a thermal electric expansion valve...
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
It would cause the low-side pressure to decrease
Technician B
Clean the condenser coil

48. What problem can cause an increase of discharge pressure and an increase of suction pressure...
Short cycling and insufficient dehumidification
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An overcharged system

49. Superheat is found in an air conditioning system in the...
('Y' and 'C') and ('G' and 'C')
Evaporator and compressor
The superheat increases and the subcooling decreases
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device

50. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
A missing air filter+improper rotation of the indoor blower+blower too small
Condenser fans operating during a low ambient condition and a low suction pressure
Technician B