Johnson Controls YVAHP072B31S, Service Manual

Page: 1440 / 1796

3-126
Service Manual
TROUBLESHOOTING
Cause Check Item
Action
(Turn OFF Main Switch)
Event
Measure superheat.
Correctly charge
refrigerant after
repairing gas leakage.
Measure and check
field-supplied pipes.
Use correct pipes.
Excessively
Low Suction
Pressure
Gas Leakage
or Shortage
of Refrigerant
Insufficient
Cooling
Operation
Excessively
Small
Diameter
Tube or
Long Piping
Check whether or not
temp. difference exists
before/after check valve.
Replace check valve
for outdoor unit.
Incorrect
Activation of
Check Valve
of Outdoor
Unit
Check temp. difference. Remove clogging.
Clogging at
Low Pressure
Piping
“Motion Sensor is
activated” is indicated
on Wired Controller
It is normal.
Activation of
Motion Sensor Control
Insufficient
Airflow to
Indoor Unit
Heat
Exchanger
Check temp. difference
at inlet and outlet of
strainer.
Replace strainer in
indoor unit.
Clogged
Strainer in
Indoor Unit
Clogging at
Low Pressure
Piping
Check for any clogging. Remove clogging.
Check connection
cord and connector.
Replace connector.
Check for clogged
air filter.
Clean air filter.
Check for obstacle at
inlet or outlet.
Remove obstacles.
Excessively
Low Air
Temp. to
Indoor Unit
Heat
Exchanger
Insufficient revolution
of indoor unit fan motor?
Replace fan motor.
Check short-circuited
indoor unit air. Remove cause of
short-circuited.
Is there operation
sound from coil?
Replace coil.
Is thermistor on
compressor normal?
Replace thermistor.
Is thermistor
installed correctly on
compressor?
Correctly install it.
Failure or
Malfunction
of Electronic
Expansion
Valve
Calculate heat load. Use a larger unit.
Indoor Heat Load is Larger
than Cooling Capacity
Abnormalities of Devices
Other
Abnormalities