Check code
4-way valve trouble in heating mode
Abnormal points and detection methods
Causes and checkpoints
Abnormal if 4-way valve does not operate during heating operation.
Abnormal when any of the following temperature conditions is satisfied for
3 min. or more during heating operation
1. TH22j−TH21j
[
−10°C [−18°F]
2. TH23j−TH21j
[
−10°C [−18°F]
3. TH22j
[
3
:
[37.4°F]
4. TH23j
[
3
:
[37.4°F]
Note:
For indoor unit, the abnormality is detected if an operating unit satisfies the
condition.
4-way valve failure
Disconnection or failure of 4-way valve coil
Clogged drain pipe
Disconnection or loose connection of connectors
Malfunction of input circuit on outdoor multi controller circuit board
Defective outdoor power circuit board
TH21: Indoor intake temperature thermistor (RT11 or TH1)
TH22: Indoor liquid pipe temperature thermistor (RT13 or TH2)
TH23: Indoor gas pipe temperature thermistor (TH-A to E)
●Diagnosis of defectives
Make sure to turn the power OFF before connecting/disconnecting any connectors, or replacing boards.
Diagnosis
Remedy
Is the connector for outdoor multi
controller circuit board or 4-way valve
coil disconnected or loose?
Reconnect the connector or connect it
tightly.
Yes
Disconnect the connector for outdoor multi
controller circuit board or 4-way valve coil
to check the resistance.
No
Replace the 4-way valve coil.
Replace the outdoor multi controller circuit
board.
Is the detected voltage normal?
Is it free from any trace of over-heating
or burning?
Is there a resistance detected?
Check the voltage and appearance of the
outdoor multi controller circuit board.
No
No
Yes
1508
(EF)
Yes
Replace the outdoor multi controller circuit
board.
63
OCH668B
Please refer to "8-5. HOW TO
CHECK THE PARTS" for ohm values.