Mitsubishi Electric MUZ-GC25VA-E1 Service Manual page 38

Outdoor base gets frozen.
Check of defrost heater
P
MUZ-GC25VAH
Check the following points before checking electric continuity.
1) Does the resistance of ambient temperature thermistor have the characteristics? Refer to 11-6.1.
2) Is the resistance of defrost heater normal? Refer to 11-4.
3) Does the heater protector remain conducted (not open)?
4) Are both ambient temperature thermistor and circuit of defrost heater securely connected to connectors?
In HEAT mode, for more than 5 minutes, let the ambient temperature thermistor continue to read 5: or below, and let
the defrost thermistor continue to read -1: or below.
Is there 230V AC between CN722 1 and 3 on the
inverter P.C. board(GC25) or power P.C.
board(GC35)? Refer to 11-6.
(MUZ-GC25VAH)
Is the voltage between CN726 2(+)-3(-)
on the power P.C. board 0V DC? Refer
to 11-6.
Replace the inverter P.C. board.
MUZ-GC35VAH
NOTE: In case both thermistors are more than the above
temperature, cool them with cold water etc...
No
(MUZ-GC35VAH)
No
No problem of the inverter P.C.
Yes
board(GC25) or power P.C.
board(GC35).
Yes
Replace the power
P.C. board.
MUZ-GC25VAH
Inverter P.C board
1 2 3
CN722
26H
H
38
MUZ-GC35VAH
Power P.C board
2 3
230V AC
CN726
3
2
1
CN722
26H
H
230V AC