Mitsubishi Electric MUZ-FD25VA-E1 Service Manual page 37

Outdoor base gets frozen.
Check of defrost heater
O
MUZ-FD25VAH MUZ-FD35VAH
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 230 VAC between CN722
inverter P.C. board? Refer to 11-6.
Replace the inverter P.C. board.
NOTE: In case both thermistors are more than the above
temperature, cool them with cold water etc...
1 3
and on the
No
Yes
No problem of the inverter
P.C. board.
37