Mitsubishi Electric MUH-GA35VB Service Manual page 25

Compressor and/or outdoor fan motor doesn't stop.
B B Check of outdoor unit
Start
Turn OFF the power supply.
After 1 minute, turn ON
power supply again.
Does compressor stop?
Yes
OK
Does outdoor fan motor stop?
Yes
OK
Unit operates COOL mode even if it is set to HEAT mode.
w First, measure the resistance of R.V. coil to confirm it is disconnected or is not short-circuit.
C C Check of R.V. coil
Unit operates HEAT mode even if it is set to COOL mode.
w First, measure the resistance of R.V. coil to confirm it is disconnected or is not short-circuit.
C C Check of R.V. coil
No Is there 230V AC between 3 on the
compressor contactor (52C) and N on the
outdoor terminal block (TB1)?
Yes
Replace the
deicer P.C. board.
No
Replace the
deicer P.C. board.
Turn ON the power supply and operate
the indoor unit in HEAT mode by pressing
the EMERGENCY OPERATION switch.
After 3 minutes, does the unit
operate in COOL mode?
Is there 230V AC between
CN7211 – 2 on the deicer P.C.
board?
Replace the R.V. coil.
Turn ON the power supply and operate
the indoor unit in COOL mode by pressing
the EMERGENCY OPERATION switch.
Yes
After 3 minutes, does the unit
operate in HEAT mode?
Yes
Is there 230V AC between
CN7211 – 2 on the deicer
P.C. board?
Yes
Replace the
deicer P.C. board.
No
Rectify the connecting wire.
No
OK
Yes
No
Replace the
deicer P.C. board
Yes
No
Ok
No
Replace the R.V. coil.
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