Hitachi Utopia RPI-2.5HRG Service Manual page 18

(1.1.6 Abnormalities of Devices)
Phenomenon
Excessively
High
Discharge
Pressure
Insufficient
Heating
Operation
Malfunction of Check Valve
of Outdoor Unit
Excessively
High Suction
Pressure
Cause
Insufficient
Air Flow to
Indoor Unit
Heat
Exchanger
Excessively
High Air
Temp. to
Indoor Unit
Heat
Exchanger
Excessively
Charged
Refrigerant
Non-
Condensate
Gas in Ref.
Cycle
Clogging of
Discharge
Pr. Piping
Malfunction or Internal
Leakage of 4-Way Valve
Malfunction
or Internal
Leakage of
4-Way Valve
Discharge Temp. of
Indoor Unit is Unstable.
Check Item
Check for filter clogging.
Check for any obstacles
at inlet or outlet of
indoor unit.
Check indoor fan speed.
Check whether or not
short-circuited air exists.
Check expansion valve
opening.
Check each temp.
and pressure.
Check for clogging.
Check temp. difference
between inlet and outlet
of 4-way valve.
Check temp. difference
between inlet and outlet
of check valve.
Check temp. difference
between inlet and outlet
of 4-way valve.
Check for expansion
valve of indoor unit in
the same system.
TROUBLESHOOTING
Action
(Turn OFF Main Switch)
Remove clogging.
Remove obstacles.
Replace fan motor.
Remove cause of
short-circuited air.
Correctly charge
refrigerant.
Recharge refrigerant
after vacuum pumping.
Remove clogging.
Replace 4-way valve.
Replace check valve.
Replace 4-way valve.
Replace failed
expansion valve of
indoor unit.
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