Hitachi RASC-4HNPE Service Manual page 289

10 Troubleshooting
Checking procedure for main parts
When the reversing valve relay is turned ON, current is applied to
the coil. After the reversing valve relay is turned OFF, no current
is applied.
Switch relay: ON
(Cooling/Heating)
4-way solenoid
valve coil
Separation
resistance
4-way solenoid valve
4-way solenoid valve relay
Cooling/Heating switch relay
279 SMGB0091 rev.2 - 11/2015
Electrical circuit
When the reversing valve relay is turned ON, current is applied to
the coil. After the reversing valve relay is turned OFF, no current
Reversing valve relay: ON
4-way solenoid
valve coil
Time Chart
Cooling operation
Defrost operation
Heating operation
SW1 is turned ON
for a second
(Occurs twice)
is applied.
Switch relay: OFF
(Cooling/Heating)
Reversing valve relay: ON
Separation
resistance
or
Heating operation
Current is carried only
when turning the reversion
valve relay ON
10