Hitachi Utopia PAS-3HVRG, Service Manual

Page: 46 / 127

TROUBLESHOOTING
1-43
Cause Check Item
Action
(Turn OFF Main Switch)
Phenomenon
Measure discharge
pressure.
Check continuity after
decreasing of pressure.
Replace it if faulty.
Faulty
Pressure
Switch
Faulty High
Pressure
Switch
Measure resistance
by tester. Repair looseness.
Replace connector. Insufficient
Contacting
Check connections. Repair connections.
Incorrect
Connection
Calculate heat load.
Reduce heat load or
use a bigger 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.
Excessively High Temp.
Air to Indoor Unit
Heat Exchanger
Activation of
High Pressure
Switch due to
Excessively
High Discharge
Pressure
during Heating
Operation
Check cycle operating
temp. Charge refrigerant
correctly.
Overcharged Refrigerant
Check ambient temp.
and pressure. Recharge refrigerant
after vacuum pumping. Mixture of Non-Condensable
Gas in Refrigerant Cycle
Check decreasing
air flow volume at
pressure switch for
control activative.
Replace thermistor
for evaporating temp.
if faulty.
Faulty of Outdoor
Fan Control
Check activated
pressure and
connecting wire. Replace it if pressure
switch for control is
faulty.
Faulty of Pressure
Switch for Control
Check for clogging. Remove clogging. Clogging of Discharge Piping
Check for clogging. Remove clogging.
Check connecting
wiring and connectors.
Replace connector.
Check operating sound
from coil.
Replace coil.
Check discharge gas
thermistor.
Check attaching
state of discharge
gas thermistor.
Replace thermistor.
Reattach thermistor.
Faulty or Malfunction of
Expansion Valve
Check stop valves. Fully open stop valve.
Liquid Line Stop Valve or
Gas Line Stop Valve are
not in Operation
Indoor Fan
Stoppage
(RPK Only)
Check continuity
of Fuse
Replace it if faulty. Melted Fuse
Replace new PCB
and check.
Replace it if faulty. Failure of PCB