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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. 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...
Both technicians are correct
Low voltage and a faulty start relay
An overcharged system
Always have some liquid present in the bulb and diaphragm
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
Technician B
A restricted metering device
Technician A is correct
3. What three things can prevent an air conditioning system from absorbing heat at the proper rate...
Technician B
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
An overcharged system
Increases starting torque
4. Which of the following can cause excessive subcooling...
It keeps a constant superheat in the evaporator
Always have some liquid present in the bulb and diaphragm
The sensing bulb at a lower temperature than the valve body
An overcharged system
5. 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
An undercharged system+insufficient airflow over the evaporator coil
An undercharged system+insufficient airflow over the evaporator coil
Whenever necessary
6. What type of problems can be caused by an oversized air conditioning system...
Short cycling and insufficient dehumidification
Low discharge pressure - high suction pressure - and low amp draw
Rise more than normal
50-65
7. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Whenever necessary
20 to 30
A start capacitor and a solid-state relay
An uninsulated suction line and a restricted metering device
8. What are the symptoms of an air conditioning system that has a low charge...
Technician B
A start relay
The low-side pressure will decrease and the evaporator coil will be partially frosted
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
9. Air filters should be replaced...
A start relay
A start capacitor and a solid-state relay
Whenever necessary
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
10. Why is it unsafe to operate an air conditioning system with a low charge...
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
Both technicians are incorrect
The discharge pressure increases and the amperage increases
11. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
50-65
An overcharged system
Whenever necessary
12. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Technician B
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Both technicians are incorrect
An undercharged system+insufficient airflow over the evaporator coil
13. 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 sensing bulb at a lower temperature than the valve body
High superheat and low discharge pressure
110-120
A dirty condenser - recirculation of condenser air - and a defective condenser fan
14. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Bad compressor valve
Contains a solenoid coil and one or more sets of contacts
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
15. Which of the following will cause excessive discharge pressures on an air conditioning system...
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
An increase of air leakage from ductwork
The sensing bulb at a lower temperature than the valve body
16. Name two symptoms that are common to an over-charged air conditioning system and a system that has a dirty condenser.
A defective circuit breaker
Technician B
The discharge pressure increases and the amperage increases
Technician A is correct
17. On an are-22 air conditioning system - the suction-line filter drier should be changed when the pressure drop dictates...
3 psig
A missing air filter+improper rotation of the indoor blower+blower too small
A low refrigerant charge
The external equalizer could be plugged
18. 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
Technician B
An acid-core suction line drier
Broken rings+broken valves+seized bearings
Both technicians are correct
19. Which of the following could be the cause for a system's discharge and suction pressure being low...
Both technicians are incorrect
A restricted metering device
Low discharge pressure - high suction pressure - and low amp draw
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
20. What problem or problems can cause the discharge pressure to be low and the suction pressure to be high...
Technician B
It keeps a constant superheat in the evaporator
Technician A is correct
Bad compressor valve
21. 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
Flooding the condenser - cycling condenser fans - and dampering condenser air
Partially frosted evaporator and high superheat
110-120
Technician B
22. 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 discharge pressure increases and the amperage increases
An uninsulated TXV sensing bulb
Technician A
The oil pump pressure and the crankcase pressure
23. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
It keeps a constant superheat in the evaporator
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
The superheat will increase and the low-side pressure will decrease
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
24. What are common methods that are used for leak-testing a system...
A vacuum test+oil traces around fittings+soap bubble solution
Low discharge pressure - high suction pressure - and low amp draw
A defective circuit breaker
Technician B
25. Insufficient airflow can be caused by...
A sensing bulb improperly connected to the suction line
Technician B
Both technicians are incorrect
An increase of air leakage from ductwork
26. When troubleshooting a split-system air conditioner - it is found that the compressor motor is humming but not starting. Technician A says that it could be an open internal overload protector. Technician B says that it could be a blown fuse. Which te
Both technicians are incorrect
A start capacitor and a solid-state relay
The oil pump pressure and the crankcase pressure
Technician B
27. What are two common symptoms of refrigerant leaks in an air conditioning system...
The low-side pressure will decrease and the evaporator coil will be partially frosted
Condenser fans operating during a low ambient condition and a low suction pressure
The low-side pressure will decrease and the evaporator coil will be partially frosted
Partially frosted evaporator and high superheat
28. The best description of a relay would be...
Contains a solenoid coil and one or more sets of contacts
The superheat will increase and the low-side pressure will decrease
20 to 30
Low discharge pressure - high suction pressure - and low amp draw
29. When a high-efficiency split air conditioning system has a plugged metering device - what symptoms might occur...
A bad thermostat
A start relay
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
30. What are two common symptoms of an overcharged air conditioning system that uses a capillary-tube-type metering device...
An increase in suction pressure and an increase in discharge pressure
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
Low discharge pressure - high suction pressure - and low amp draw
31. 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 vacuum test+oil traces around fittings+soap bubble solution
Technician B
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
32. What controls are used on air conditioning or refrigeration systems that incorporate an automatic pump-down system...
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
Technician A is correct
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
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 missing air filter+improper rotation of the indoor blower+blower too small
110-120
A bad thermostat
Both technicians are incorrect
34. What is the common cause of a compressor burnout...
The superheat increases and the subcooling decreases
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High superheat and low discharge pressure
An increase in low-side pressure
35. 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
Always have some liquid present in the bulb and diaphragm
Evaporator and compressor
An open internal overload protector
36. Which of the following is a common cause of an excessively low superheat on a TXV system...
The superheat will increase and the low-side pressure will decrease
A vacuum test+oil traces around fittings+soap bubble solution
A sensing bulb improperly connected to the suction line
Run with high head and high suction pressure
37. 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...
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38. A customer calls with an insufficient cooling complaint on a 90
Technician B
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
A restricted metering device
An undercharge and low ambient conditions
39. What problem can cause an increase of discharge pressure and an increase of suction pressure...
The internal overload is opened
The sensing bulb at a lower temperature than the valve body
An overcharged system
The superheat increases and the subcooling decreases
40. 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
Technician A is correct
A defective circuit breaker
A low refrigerant charge
The sight glass is full of liquid+the sight glass is full of gas
41. 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...
A low refrigerant charge
Condenser fans operating during a low ambient condition and a low suction pressure
110-120
The internal overload is opened
42. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
A plugged filter drier
Partially frosted evaporator and high superheat
Technician B
The system has been overcharged+The system has air trapped in the condenser
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
A blown fuse
A blown fuse
Technician B
An overcharged system
44. 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
Rise more than normal
A blown fuse
A defective circuit breaker
45. 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...
Condenser fans operating during a low ambient condition and a low suction pressure
Rise more than normal
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
A missing air filter+improper rotation of the indoor blower+blower too small
46. A system that is operating with a clear sight glass shows...
An increase in low-side pressure
An overcharged system
An uninsulated TXV sensing bulb
The sight glass is full of liquid+the sight glass is full of gas
47. What causes the automatic expansion valve to close...
An increase in low-side pressure
Technician B
A missing air filter+improper rotation of the indoor blower+blower too small
Increases starting torque
48. Which of the following problems can cause a decrease in a system's pressures and possible icing of the evaporator coil...
Both technicians are correct
A low refrigerant charge
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
A missing air filter+improper rotation of the indoor blower+blower too small
49. 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
Evaporator and compressor
Broken rings+broken valves+seized bearings
An acid-core suction line drier
50. Superheat is found in an air conditioning system in the...
Evaporator and compressor
('Y' and 'C') and ('G' and 'C')
A restricted metering device
A defective circuit breaker
Sorry!:) No result found.
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