Hitachi RAS-H(V)RNME-AF Service Manual page 381

12 Troubleshooting
Phenomenon
Excessively high temperature air to
outdoor unit heat exchanger
Activation of Faulty high
high pressure
pressure
switch due to
switch
excessively
high discharge
pressure during
cooling
operation
Mixture of non-condensable
Clogging of discharge piping
Liquid line stop valve or gas line
stop valve are not in operation
N O T E
This alarm code is indicated when the outdoor unit protective device is activated by high discharge pressure du-
ring 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.
371
SMGB0070 rev. 1 - 08/2011
Cause
Insufficient air flow to heat
exchanger of outdoor unit
Faulty pressu-
re switch
Insufficient
contacting
Incorrect
connection
Overcharged refrigerant
gas in refrigerant cycle
Faulty or malfunction of
expansion valve
Locking up outdoor unit
expansion valve closure
Check item
Clogging of heat
exchanger?
Check for dust on
air filter
Check the service
space
Check for speed:
Outdoor fan: cooling
Indoor fan: heating
Check for hot air near
the ceiling
Check for short
circuited air
Check for other heat
source
Check for short
circuited air
Check for other heat
source
Check connections
Check cycle operating
temperature
Check ambient tempe-
rature and pressure
Check for clogging
Check for clogging
Check connecting wiring
and connectors
Check discharge gas
thermistor
Check discharge gas
thermistor
Check attaching state of
discharge gas
thermistor
Check stop valves
Check expansion valve
actuation
Action
(Turn OFF the main switch)
Remove clogging
Remove dust
Secure service space
Replace fan motor if faulty
Make good circulation
Remove short circuited air
Remove heat source
Remove short-circuited air
Remove heat source
Repair connections
Charge refrigerant correctly
Recharge refrigerant after
vacuum pumping
Remove clogging
Remove clogging
Replace connector
Replace coil
Replace thermistor
Reattach thermistor
Fully open stop valve
Replace outdoor
expansion valve
12