Hitachi RAS-(3-6)HVNC1(E) - Page 269

8 Troubleshooting
255
SMGB0087 rev.0 - 12/2013
8
Phenomenon Cause Check item
Action
(Turn OFF main switch)
Activation of high pressure
switch due to excessively
high discharge pressure dur-
ing cooling operation
Insufcient air ow to heat ex-
changer of outdoor unit
Clogging of Heat Exchanger? Remover clogging
Check for dust on air lter Remove dust
Check the service space Secure service space
Check for outdoor fan speed Replace fan motor if faulty
Excessively high temperature air
to outdoor unit heat exchanger
Check for hot air near the
ceiling
Make good circulation
Check for short circuited air Remove short-circuited air
Check for other heat source Remove heat source
Faulty high
pressure
switch
Faulty
pressure
switch
Measure discharge pressure.
Check continuity after
decreasing of pressure
Replace it if faulty
Insufcient
contacting
Measure resistance by tester
Repair looseness.
Replace connector
Incorrect
connection
Check connections Repair connections
Overcharged refrigerant
Check cycle operating
temperature
Charge refrigerant correctly
Mixture of non-condensable gas
in refrigerant cycle
Check ambient temperature
and pressure
Recharge refrigerant after
vacuum pumping
Clogging of discharge piping Check for clogging Remove clogging
Faulty or malfunction of
expansion valve
Check for clogging Remove clogging
Check connecting wiring and
connectors
Replace connector
Check operating sound from
coil
Replace coil
Check discharge gas
thermistor
Replace thermistor
Check attaching state of
discharge gas thermistor
Reattach thermistor
Liquid line stop valve or gas line
stop valve are not in operation
Check stop valves Fully open stop valve
Locking up outdoor unit
expansion valve closure
Check expansion valve
actuation
Replace outdoor expansion valve
N O T E
This alarm code is indicated when the outdoor unit protective device is activated by high discharge pressure during cooling
operation. Accordingly, when this alarm code is indicated, there is high possibility of high pressure switch actuation and the
above troubleshooting actions are based on such cases.