NATE: Air Conditioning
Troubleshooting CORRECT 100%
What are the symptoms of a TXV air conditioning system if it has lost its charge: - ANSWERThe
superheat will increase and the low-side pressure will decrease
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 the air filter is clean. The condenser fan on the
outdoor unit is operating, but he or she notices that the liquid line is hot to the touch. Before
connecting gauges to the system, the next step should be to: - ANSWERclean the condenser coil
What are the symptoms of an air conditioning system that has a low charge: - ANSWERThe low-side
pressure will decrease and the evaporator coil will be partially frosted
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 says that it is possibly a dirty air filter. Which
technician is more likely to be correct: - ANSWERtechnician B
What are the operating pressures of an oil pressure safety switch: - ANSWERthe oil pump pressure
and the crankcase pressure
What is a common discharge temperature of an air-cooled air conditioning system that is used on a
90° F day: - ANSWER110-120° F
What are the symptoms of an air conditioning system that has a bad compressor discharge valve: -
ANSWERlow discharge pressure, high suction pressure, and low amp draw
What is the purpose of an EPR valve: - ANSWERIt increases pressure in a high-temperature
evaporator coil when it is used on a dual-evaporator system
Which of the following is a possible cause for a compressor to overheat: - ANSWERa low refrigerant
charge
, What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer: -
ANSWERa plugged filter drier
What causes the automatic expansion valve to close: - ANSWERan increase in low-side pressure
A customer calls with an insufficient cooling complaint on a 90° F day. Upon arrival it is found that
the system, using R-22, is operating at 50 psig on the low side and 150 psig on the high side. Further
investigation indicates that the evaporator coil is partially frosted on one circuit of the distributor.
Technician A says that the system has a low charge and must be leak-tested. Technician B says that
the capillary tube from the distributor is partially restricted. Which technician is correct: -
ANSWERtechnician B
What type of problems can be caused by an oversized air conditioning system: - ANSWERshort
cycling and insufficient dehumidification
What types of symptoms will be present if the sensing bulb of a TXV is not properly connected: -
ANSWERhigh suction pressure and low superheat
An air conditioning unit has a suction line that is frosted up to the compressor. What faults could
cause this to occur: - ANSWERa dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Name two symptoms that are common to an over-charged air conditioning system and a system that
has a dirty condenser. - ANSWERThe discharge pressure increases and the amperage increases
When an air conditioning system has an undercharge, what happens to the superheat and the
subcooling of the system: - ANSWERThe superheat increases and the subcooling decreases
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: - ANSWERa blown fuse
A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that
the system is using R-22 with the high-side pressure at 290 psig and the low-side pressure at 85 psig.
The ambient temperature is 85° F and the indoor wet bulb (WB) is 60° F. Technician A says that, more
than likely, the condenser is dirty. Technician B says that the system's pressures are common for this
type of day. Who is correct: - ANSWERtechnician A
Troubleshooting CORRECT 100%
What are the symptoms of a TXV air conditioning system if it has lost its charge: - ANSWERThe
superheat will increase and the low-side pressure will decrease
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 the air filter is clean. The condenser fan on the
outdoor unit is operating, but he or she notices that the liquid line is hot to the touch. Before
connecting gauges to the system, the next step should be to: - ANSWERclean the condenser coil
What are the symptoms of an air conditioning system that has a low charge: - ANSWERThe low-side
pressure will decrease and the evaporator coil will be partially frosted
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 says that it is possibly a dirty air filter. Which
technician is more likely to be correct: - ANSWERtechnician B
What are the operating pressures of an oil pressure safety switch: - ANSWERthe oil pump pressure
and the crankcase pressure
What is a common discharge temperature of an air-cooled air conditioning system that is used on a
90° F day: - ANSWER110-120° F
What are the symptoms of an air conditioning system that has a bad compressor discharge valve: -
ANSWERlow discharge pressure, high suction pressure, and low amp draw
What is the purpose of an EPR valve: - ANSWERIt increases pressure in a high-temperature
evaporator coil when it is used on a dual-evaporator system
Which of the following is a possible cause for a compressor to overheat: - ANSWERa low refrigerant
charge
, What is a possible cause of a sweat or frost pattern downstream from a sight glass and filter dryer: -
ANSWERa plugged filter drier
What causes the automatic expansion valve to close: - ANSWERan increase in low-side pressure
A customer calls with an insufficient cooling complaint on a 90° F day. Upon arrival it is found that
the system, using R-22, is operating at 50 psig on the low side and 150 psig on the high side. Further
investigation indicates that the evaporator coil is partially frosted on one circuit of the distributor.
Technician A says that the system has a low charge and must be leak-tested. Technician B says that
the capillary tube from the distributor is partially restricted. Which technician is correct: -
ANSWERtechnician B
What type of problems can be caused by an oversized air conditioning system: - ANSWERshort
cycling and insufficient dehumidification
What types of symptoms will be present if the sensing bulb of a TXV is not properly connected: -
ANSWERhigh suction pressure and low superheat
An air conditioning unit has a suction line that is frosted up to the compressor. What faults could
cause this to occur: - ANSWERa dirty evaporator coil+a plugged air filter+a bad indoor blower relay
Name two symptoms that are common to an over-charged air conditioning system and a system that
has a dirty condenser. - ANSWERThe discharge pressure increases and the amperage increases
When an air conditioning system has an undercharge, what happens to the superheat and the
subcooling of the system: - ANSWERThe superheat increases and the subcooling decreases
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: - ANSWERa blown fuse
A customer calls with an insufficient cooling complaint. Upon arrival to the service call it is found that
the system is using R-22 with the high-side pressure at 290 psig and the low-side pressure at 85 psig.
The ambient temperature is 85° F and the indoor wet bulb (WB) is 60° F. Technician A says that, more
than likely, the condenser is dirty. Technician B says that the system's pressures are common for this
type of day. Who is correct: - ANSWERtechnician A
