Mitsubishi Electric Mr.Slim MSH24WN Service Manual page 38

Compressor and / or outdoor fan motor doesn't stop.
Check of outdoor unit
E
1 Turn OFF the power supply.
2 After 30 seconds, turn ON the power supply again.
3 Operate the unit in COOL or HEAT mode by
pressing the EMERGENCY OPERATION switch.
4 Operate the unit for 1 minute or more and stop it by
pressing the EMERGENCY OPERATION switch again.
After 30 seconds,
does compressor stop?
After 30 seconds, does
outdoor fan motor stop?
Unit operates COOL mode even if it is set to HEAT mode.
Check of R.V. coil
F
w First, measure the resistance of R.V. coil to confirm it is disconnected or is not short-circuit.
Disconnect the TAB52 on the deicer P.C. board.
Turn ON the power supply and operate
the indoor unit in HEAT mode by pressing
the EMERGENCY OPERATION switch.
Unit operates HEAT mode even if it is set to COOL mode.
Check of R.V. coil
F
w First, measure the resistance of R.V. coil to confirm it is disconnected or is not short-circuit.
Disconnect the TAB52 on the deicer P.C. board.
Turn ON the power supply and operate
the indoor unit in COOL mode by pressing
the EMERGENCY OPERATION switch.
Is there 208/230V AC
No
between A1-A2 on the
compressor contactor?
Yes
Ok
Replace the
deicer P.C. board.
No
Replace the
deicer P.C. board.
Yes
Ok
After 3 minutes, is there No
208/230V AC between CN721
1-3 on the deicer P.C. board?
Yes
Replace the R.V. coil.
After 3 minutes, is there
No
208/230V AC between CN721
1-3 on the deicer P.C. board?
Yes
Replace the
deicer P.C. board.
Is there 208/230V AC
No between 2/T1 on the
compressor contactor (52C)
and on the outdoor
L2
terminal block?
Yes
Replace the compressor
contactor (52C).
Replace the
deicer P.C. board.
Replace the R.V. coil.
38
No
Make the connection
of wiring correct.
Yes