Hitachi RAS-H(V)RNME-AF Service Manual page 384

12 Troubleshooting
Phenomenon
Faulty high
pressure
Activation of
high pressure
switch due to
excessively
high discharge
pressure during
heating
operation
Mixture of non-condensable gas in
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 heating 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.
374
SMGB0070 rev. 1 - 08/2011
Cause
Insufficient water flow to
indoor unit heat exchanger
Faulty
pressure
switch
Insufficient
switch
contacting
Incorrect
connection
Faulty of outdoor fan control
Faulty of pressure switch
for control
Overcharged refrigerant
refrigerant cycle
Clogging of discharge piping
Faulty or malfunction of
expansion valve
Check item
Clogging of water
strainer
Check for any obstacle
at inlet or outlet of
heat exchanger
Check water pump
Measure discharge
pressure.
Check continuity after
decreasing of pressure.
Measure resistance
by tester
Check connections
Check decreasing air
flow volume at pressure
switch for control
activative.
Check activated
pressure and
connecting wire.
Check cycle operating
temperature.
Check ambient tempe-
rature and pressure.
Check for clogging.
Check for clogging.
Check connecting wiring
and connectors.
Check operating sound
from coil.
Check discharge gas
thermistor.
Check attaching state of
discharge
gas thermistor.
Check stop valves.
Action
(Turn OFF the main switch)
Water strainer maintenance
Remove it
Replace water pump
Replace it if faulty.
Repair looseness.
Replace connector.
Repair connections.
Replace thermistor for evapo-
rating temperature if faulty.
Replace it if pressure switch
for control is faulty.
Charge refrigerant correctly.
Recharge refrigerant after
vacuum pumping.
Remove clogging.
Remove clogging.
Replace connector.
Replace coil.
Replace thermistor.
Reattach thermistor.
Fully open stop valve.