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Test your basic knowledge |
NATE Air Conditioning Troubleshooting
Start Test
Study First
Subjects
:
engineering
,
nate
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...
Broken rings+broken valves+seized bearings
Technician A
A sensing bulb improperly connected to the suction line
A vacuum test+oil traces around fittings+soap bubble solution
2. A restricted air filter in an air conditioning system can be identified by...
Low superheat
Both technicians are correct
The system has been overcharged+The system has air trapped in the condenser
Flooding the condenser - cycling condenser fans - and dampering condenser air
3. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...
4. What are two common symptoms of a rooftop air conditioning system that operates with a reverse-acting high-pressure control stuck in the closed position...
Technician B
Flooding the condenser - cycling condenser fans - and dampering condenser air
Condenser fans operating during a low ambient condition and a low suction pressure
An increase in low-side pressure
5. Which of the following is a common cause of an excessively low superheat on a TXV system...
A blown fuse
The superheat increases and the subcooling decreases
A start relay
A sensing bulb improperly connected to the suction line
6. A split-system air conditioner that uses a piston-type metering device is to be charged with are-22. Technician A says that the outdoor dry-bulb temperature is needed to determine the proper superheat. Technician B says that the indoor wet-bulb tempe
A blown fuse
Both technicians are correct
('Y' and 'C') and ('G' and 'C')
110-120
7. The best description of a relay would be...
An uninsulated TXV sensing bulb
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Contains a solenoid coil and one or more sets of contacts
A bad thermostat
8. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
The oil pump pressure and the crankcase pressure
High superheat and low discharge pressure
Technician B
9. 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
The system has been overcharged+The system has air trapped in the condenser
High suction pressure and low superheat
Technician B
3 psig
10. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A start capacitor and a solid-state relay
A dirty condenser - recirculation of condenser air - and a defective condenser fan
11. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
A start capacitor and a solid-state relay
50-65
A restricted metering device
12. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
Low discharge pressure - high suction pressure - and low amp draw
20 to 30
An increase in low-side pressure
3 psig
13. What problem can cause an increase of discharge pressure and an increase of suction pressure...
A start relay
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The internal overload is opened
An overcharged system
14. What is the purpose of a CPR valve...
Technician B
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
It is used to control refrigerant pressure in the compressor crankcase
The system has been overcharged+The system has air trapped in the condenser
15. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
A vacuum test+oil traces around fittings+soap bubble solution
The oil pump pressure and the crankcase pressure
16. A customer calls and says that her air conditioning system is not cooling properly. Upon arrival - a technician notices that the suction line and compressor have frost buildup. Technician A says that the problem is probably a low charge. Technician B
Broken rings+broken valves+seized bearings
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated suction line and a restricted metering device
Technician B
17. 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
Technician B
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
High superheat and low discharge pressure
50-65
18. 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 bad thermostat
An acid-core suction line drier
An uninsulated suction line and a restricted metering device
The sensing bulb at a lower temperature than the valve body
19. A restricted air filter in an air conditioning system can be identified by...
Evaporator and compressor
'G' to 'C'
Low superheat
An increase of air leakage from ductwork
20. What is a common discharge temperature of an air-cooled air conditioning system that is used on a 90
The sight glass is full of liquid+the sight glass is full of gas
An overcharged system
The external equalizer could be plugged
110-120
21. When testing an indoor blower control circuit and the cooling circuit on a fan center - what terminals should read 24 volts if the air conditioning system is in operation...
22. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The superheat increases and the subcooling decreases
Technician B
An overcharged system
Run with high head and high suction pressure
23. What are the symptoms of an air conditioning system that has a low charge...
An overcharged system
The oil pump pressure and the crankcase pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
An uninsulated suction line and a restricted metering device
24. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
The superheat increases and the subcooling decreases
Short cycling and insufficient dehumidification
A plugged filter drier
Both technicians are incorrect
25. 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
Both technicians are correct
('Y' and 'C') and ('G' and 'C')
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
26. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
27. What are the symptoms of a TXV air conditioning system if it has lost its charge...
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
Low discharge pressure - high suction pressure - and low amp draw
The superheat will increase and the low-side pressure will decrease
28. Air filters should be replaced...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
A sensing bulb improperly connected to the suction line
Whenever necessary
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
29. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Broken rings+broken valves+seized bearings
The sensing bulb at a lower temperature than the valve body
The discharge pressure increases and the amperage increases
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 has been overcharged+The system has air trapped in the condenser
An increase in low-side pressure
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Bad compressor valve
31. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Bad compressor valve
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An increase of air leakage from ductwork
32. A system that uses a thermal electric expansion valve...
The sensing bulb at a lower temperature than the valve body
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
An undercharged system+insufficient airflow over the evaporator coil
An increase in low-side pressure
33. What are two common symptoms of refrigerant leaks in an air conditioning system...
Partially frosted evaporator and high superheat
It is used to control refrigerant pressure in the compressor crankcase
Low discharge pressure - high suction pressure - and low amp draw
Current in the compressor circuit
34. Superheat is found in an air conditioning system in the...
Short cycling and insufficient dehumidification
Evaporator and compressor
An increase of air leakage from ductwork
Run with high head and high suction pressure
35. 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
The sensing bulb at a lower temperature than the valve body
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Flooding the condenser - cycling condenser fans - and dampering condenser air
36. 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
Run with high head and high suction pressure
Lack of airflow
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Broken rings+broken valves+seized bearings
37. 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
Both technicians are incorrect
The sight glass is full of liquid+the sight glass is full of gas
A start capacitor and a solid-state relay
Technician B
38. 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
Whenever necessary
Both technicians are incorrect
Technician A
Increases starting torque
39. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
The discharge pressure increases and the amperage increases
Technician A is correct
Bad compressor valve
Partially frosted evaporator and high superheat
40. A liquid-charged TXV bulb will...
Always have some liquid present in the bulb and diaphragm
Technician A
Contains a solenoid coil and one or more sets of contacts
Clean the condenser coil
41. 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
The external equalizer could be plugged
An uninsulated suction line and a restricted metering device
Bad compressor valve
Both technicians are incorrect
42. Which of the following is a possible cause for a compressor to overheat...
Technician B
A start relay
A low refrigerant charge
An overcharged system
43. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
A missing air filter+improper rotation of the indoor blower+blower too small
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Rise more than normal
High suction pressure and low superheat
44. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
A restricted metering device
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A start relay
A plugged filter drier
45. Which of the following can cause excessive subcooling...
An overcharged system
A dirty condenser - recirculation of condenser air - and a defective condenser fan
The sight glass is full of liquid+the sight glass is full of gas
High superheat and low discharge pressure
46. What are two problems that can cause an air conditioning system to have an excessively high superheat...
('Y' and 'C') and ('G' and 'C')
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An uninsulated suction line and a restricted metering device
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
47. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Low discharge pressure - high suction pressure - and low amp draw
Technician B
Technician B
48. What are the operating pressures of an oil pressure safety switch...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
Dirty condenser - bent condenser fins - and air recirculating over the condenser
The system has been overcharged+The system has air trapped in the condenser
The oil pump pressure and the crankcase pressure
49. 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
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Technician B
The external equalizer could be plugged
Clean the condenser coil
50. 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 plugged air filter+a bad indoor blower relay
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
An undercharged system+insufficient airflow over the evaporator coil
('Y' and 'C') and ('G' and 'C')