Hitachi RAS-(3-6)HVRNM2E - Page 263

8 Troubleshooting
253
SMGB0064 rev.0 - 08/2011
8
Phenomenon Cause Check item
Action
(Turn OFF main switch)
Activation of high pressure
switch due to excessively high
discharge pressure during
cooling operation
Insufcient air ow to heat
exchanger 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 speed:
Outdoor fan: cooling
Indoor fan: heating
Replace fan motor if faulty
Excessively high temp. 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 temp. Charge refrigerant correctly
Mixture of non-condensable gas in
refrigerant cycle
Check ambient temp. 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 pres-
sure switch actuation and the above troubleshooting actions are based on such cases.