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Test your basic knowledge |
NATE Air Conditioning Troubleshooting
Start Test
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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 two common problems that can cause a sight glass in an air conditioning to have bubbles...
Bad compressor valve
Current in the compressor circuit
An increase of air leakage from ductwork
An undercharge and low ambient conditions
2. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
High suction pressure and low superheat
An undercharge and low ambient conditions
Lack of airflow
3. 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
It would cause the low-side pressure to decrease
An uninsulated TXV sensing bulb
A dirty evaporator coil - a defective evaporator fan - and an iced-up evaporator coil
4. A commercial customer calls on a 90
Dirty condenser - bent condenser fins - and air recirculating over the condenser
An uninsulated TXV sensing bulb
('Y' and 'C') and ('G' and 'C')
The system has been overcharged+The system has air trapped in the condenser
5. The temperature range of the suction line from an air conditioning system should be...
50-65
The discharge pressure increases and the amperage increases
An open internal overload protector
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
6. What are two common symptoms of refrigerant leaks in an air conditioning system...
Technician B
Partially frosted evaporator and high superheat
Condenser fans operating during a low ambient condition and a low suction pressure
3 psig
7. What component is most often the cause of a start capacitor failure...
A missing air filter+improper rotation of the indoor blower+blower too small
The superheat will increase and the low-side pressure will decrease
A defective circuit breaker
A start relay
8. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
Low discharge pressure - high suction pressure - and low amp draw
The superheat will increase and the low-side pressure will decrease
Can use the thermal electric expansion valve instead of a liquid-line solenoid as part of the pump-down system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
9. Superheat is found in an air conditioning system in the...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The low-side pressure will decrease and the evaporator coil will be partially frosted
Evaporator and compressor
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
10. 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 low-side pressure will decrease and the evaporator coil will be partially frosted
An undercharged system+insufficient airflow over the evaporator coil
The internal overload is opened
An uninsulated suction line and a restricted metering device
11. Which of the following is a possible cause for a compressor to overheat...
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Condenser fans operating during a low ambient condition and a low suction pressure
A low refrigerant charge
It increases pressure in a high-temperature evaporator coil when it is used on a dual-evaporator system
12. When an air conditioning system has an undercharge - what happens to the superheat and the subcooling of the system...
The external equalizer could be plugged
Technician B
High superheat and low discharge pressure
The superheat increases and the subcooling decreases
13. 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...
A blown fuse
The superheat increases and the subcooling decreases
Evaporator and compressor
High superheat and low discharge pressure
14. 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 vacuum test+oil traces around fittings+soap bubble solution
Partially frosted evaporator and high superheat
Technician B
Rise more than normal
15. Insufficient airflow can be caused by...
Both technicians are correct
An increase in suction pressure and an increase in discharge pressure
An undercharge and low ambient conditions
An increase of air leakage from ductwork
16. 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
Technician A
An undercharged system+insufficient airflow over the evaporator coil
Low discharge pressure - high suction pressure - and low amp draw
The sensing bulb at a lower temperature than the valve body
17. The internal overload of an air conditioning compressor senses winding temperature and...
An increase in low-side pressure
The sight glass is full of liquid+the sight glass is full of gas
Current in the compressor circuit
Short cycling and insufficient dehumidification
18. 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...
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
Condenser fans operating during a low ambient condition and a low suction pressure
Flooding the condenser - cycling condenser fans - and dampering condenser air
19. A restricted air filter in an air conditioning system can be identified by...
Low superheat
20 to 30
A vacuum test+oil traces around fittings+soap bubble solution
Both technicians are incorrect
20. 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
A defective circuit breaker
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Broken rings+broken valves+seized bearings
Short cycling and insufficient dehumidification
21. Which of the following is a possible cause for a compressor to overheat...
Technician B
A low refrigerant charge
A thermostat cycles the liquid-line solenoid - and a low-pressure switch controls the compressor
Low superheat
22. What are three methods for controlling a system's high-side pressure during low ambient conditions...
An increase of air leakage from ductwork
Flooding the condenser - cycling condenser fans - and dampering condenser air
('Y' and 'C') and ('G' and 'C')
An uninsulated TXV sensing bulb
23. What are the operating pressures of an oil pressure safety switch...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The oil pump pressure and the crankcase pressure
Both technicians are incorrect
24. Which of the following could be the cause for a system's discharge and suction pressure being low...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
A missing air filter+improper rotation of the indoor blower+blower too small
Rise more than normal
A restricted metering device
25. Air filters should be replaced...
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
Whenever necessary
Technician B
26. 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
A missing air filter+improper rotation of the indoor blower+blower too small
A blown fuse
A bad thermostat
Broken rings+broken valves+seized bearings
27. A rooftop package system keeps tripping out on the high-pressure switch. What are three possible causes for this problem...
Partially frosted evaporator and high superheat
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Always have some liquid present in the bulb and diaphragm
110-120
28. 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 plugged filter drier
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
Technician B
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
29. 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 blown fuse
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
Current in the compressor circuit
Clean the condenser coil
30. What are the operating pressures of an oil pressure safety switch...
The oil pump pressure and the crankcase pressure
Increases starting torque
The internal overload is opened
A start capacitor and a solid-state relay
31. What are possible problems that can cause the discharge-line temperature on an air conditioning system to be cool to the touch...
An overcharged system
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
It can seize the compressor because of excessive heat+It can seize the compressor because of lack of lubrication
The system was improperly serviced and it has air trapped in the condenser or the unit has been overcharged
32. What causes the automatic expansion valve to close...
Technician B
An increase in low-side pressure
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Current in the compressor circuit
33. 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
Current in the compressor circuit
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
The external equalizer could be plugged
It keeps a constant superheat in the evaporator
34. 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 discharge pressure increases and the amperage increases
It would cause the low-side pressure to decrease
A defective circuit breaker
A blown fuse
35. If a TXV sensing bulb had lost its charge - what effect would this have on the air conditioning system...
The system could be undercharged+The compressor could have bad valves+The system could have a restricted metering device
The system has been overcharged+The system has air trapped in the condenser
It keeps a constant superheat in the evaporator
It would cause the low-side pressure to decrease
36. 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
Technician B
Technician B
High superheat and low discharge pressure
37. A system that is operating with a clear sight glass shows...
A dirty evaporator coil+a plugged air filter+a bad indoor blower relay
The sight glass is full of liquid+the sight glass is full of gas
Rise more than normal
Always have some liquid present in the bulb and diaphragm
38. What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer...
Both technicians are correct
A restricted metering device
A plugged filter drier
An open internal overload protector
39. 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
Technician B
Condenser fans operating during a low ambient condition and a low suction pressure
The external equalizer could be plugged
40. What is the common cause of a compressor burnout...
Improper system evacuation during installation+short cycling of the system+excessively dirty condenser
An overcharged system
It is used to control refrigerant pressure in the compressor crankcase
An uninsulated TXV sensing bulb
41. What three things can prevent an air conditioning system from releasing heat at the proper rate...
An overcharged system
The oil pump pressure and the crankcase pressure
A dirty condenser - recirculation of condenser air - and a defective condenser fan
An overcharged system
42. The best description of a relay would be...
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Contains a solenoid coil and one or more sets of contacts
Dirty condenser - bent condenser fins - and air recirculating over the condenser
Lack of airflow
43. 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 discharge pressure increases and the amperage increases
An overcharged system
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
Technician B
44. What are two problems that can cause an air conditioning system to have an excessively high superheat...
Condenser air being recirculated over the condenser+air trapped in the condenser due to poor service procedures+an overcharged air conditioning system
Both technicians are incorrect
Partially frosted evaporator and high superheat
An uninsulated suction line and a restricted metering device
45. 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
A low amp draw - a decrease in high-side pressure - and a decrease in low-side pressure
The system has been overcharged+The system has air trapped in the condenser
Short cycling and insufficient dehumidification
46. What are the symptoms of an air conditioning system that has a bad compressor discharge valve...
An overcharged system
Run with high head and high suction pressure
High superheat and low discharge pressure
Low discharge pressure - high suction pressure - and low amp draw
47. What are two common symptoms of refrigerant leaks in an air conditioning system...
High suction pressure and low superheat
Partially frosted evaporator and high superheat
An increase of air leakage from ductwork
A start capacitor and a solid-state relay
48. What is a common temperature difference between the condensing temperature on an air-cooled condensing unit and the outdoor ambient temperature...
Increases starting torque
The superheat increases and the subcooling decreases
20 to 30
Technician B
49. 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
A defective circuit breaker
Lack of airflow
An open internal overload protector
An acid-core suction line drier
50. 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
Whenever necessary
110-120
Clean the condenser coil
Technician B
Can you answer 50 questions in 15 minutes?
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