Ground - Mitsubishi Electric City Multi PUMY-SP112VKM Technical & Service Manual

Check code
1508
(EF)
Abnormal points and detection methods
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.
●Diagnosis of defectives
Make sure to turn the power OFF before connecting/disconnecting any connectors, or replacing boards.
Is the connector for outdoor multi
controller circuit board or 4-way valve
coil disconnected or loose?
Disconnect the connector for outdoor multi
controller circuit board or 4-way valve coil
to check the resistance.
Is there a resistance detected?
Check the voltage and appearance of the
outdoor multi controller circuit board.
Is the detected voltage normal?
Is it free from any trace of over-heating
OCH668B
4-way valve trouble in heating mode
Diagnosis
No
Please refer to "8-5. HOW TO
CHECK THE PARTS" for ohm values.
Yes
or burning?
Yes
Causes and checkpoints
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)
Reconnect the connector or connect it
Yes
tightly.
No Replace the 4-way valve coil.
Replace the outdoor multi controller circuit
No
board.
Replace the outdoor multi controller circuit
board.
63
Remedy