Hitachi RAS-(3-6)HVNC1(E) - Page 271

8 Troubleshooting
257
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 during
Heating Operation
Insufcient Air Flow to Heat
Exchanger of Indoor Unit
Clogging of Heat Exchanger
Remove it
Check for dust on air lter
Check for any obstacle at inlet
or outlet of heat exchanger
Check the service space Secure service space
Check for indoor fan speed Replace fan motor if faulty
Activation of High Pressure
Switch due to Excessively High
Discharge Pressure during
Heating Operation
Excessively High Temperature
Air to Indoor Unit Heat Ex-
changer
Calculate heat load
Reduce heat load or use a big-
ger unit
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 decreas-
ing of pressure
Replace it if faulty
Insufcient
contacting
Measure resistance by tester
Repair looseness.
Replace connector
Incorrect
connection
Check connections Repair connections
Faulty of Outdoor Fan Control
Check decreasing air ow
volume at pressure switch for
control activative
Replace thermistor for
evaporating temperature if
faulty
Faulty of Pressure Switch for
Control
Check activated pressure and
connecting wire
Replace it if pressure switch for
control is faulty
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
N O T E
This alarm code is indicated when the outdoor unit protective device is activated by high discharge pressure during 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.