Johnson Controls YVAHP072B31S, Service Manual

Page: 1441 / 1796

Service Manual
3-127
TROUBLESHOOTING
Abnormalities of Devices
Other
Abnormalities
Cause Check Item
Action
(Turn OFF Main Switch)
Event
Excessively
High
Discharge
Pressure
Insufficient
Cooling
Operation
Check expansion valve
opening.
Correctly charge
refrigerant.
Excessively
Charged
Refrigerant
Excessively
High Air
Temp. to
Outdoor Unit
Heat
Exchanger
Check each temp.
and pressure. Charge refrigerant
after vacuum pumping.
Non-
Condensable
Gas in Cycle
Check for clogging. Remove clogging.
Clogging of
Discharge
Piping
Check clogging of
outdoor unit
heat exchanger.
Remove clogging.
Obstacles at inlet or
outlet of outdoor unit
heat exchanger?
Remove obstacles.
Short-circuited
outdoor unit Remove cause of
short-circuit.
Any other heat load
near outdoor unit?
Remove heat source.
Is service space for
outdoor unit sufficient?
Secure sufficient
service space.
Correct fan speed? Replace fan motor.
Insufficient
Airflow to
Outdoor Unit
Heat
Exchanger
Check for clogging. Remove clogging.
Check for connecting
wire and connector.
Replace connector.
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 Expansion
Valve
Check temp. difference
between inlet and
outlet of reversing valve.
Check leakage from
solenoid valve.
Excessively
Low Suction
Pressure
Failure of
Solenoid
Valve
for Bypass
Replace solenoid valve.
Replace failed
expansion valve of
indoor unit.
Replace reversing valve.
Malfunction
or Internal
Leakage from
Reversing
Valve
Check temp. difference
between inlet and outlet
of reversing valve.
Replace reversing valve.
Malfunction or Internal
Leakage from Reversing Valve
Check for expansion
valve of indoor unit in
the same system.
Discharge Temp. of
Indoor Unit is Unstable.
outdoor unit air