Mitsubishi Electric MXZ-2A20NA - 1, Service Manual

Page: 94 / 138

94
Check of HPS
Infinity
0 Ω
No
Yes
1. Disconnect the connector CN681 in the electronic control P.C. board.
2. Check the resistance of HPS after 1 minute has passed since the outdoor unit power supply was turned OFF.
Check the resistance between
each terminal.
Reconnect CN681.
Turn ON the power supply to the indoor and outdoor unit.
3 minutes later, start EMERGENCY OPERATION.
Is HPS protection displayed
immediately after compressor
starts ?
Replace HPS.
Replace the electronic control P.C. board.
Normal
The other cases
Indoor unit does not operate. (different operating models in multi system)
• When you try to run two indoor units simultaneously, one for cooling and the other for heating, the unit which
transmits signal to the outdoor units first decides the operation mode.
• When the above situation occurs, set all the indoor units to the same mode, turn OFF the indoor units, and
then turn them back ON.
• Though the top of the indoor unit sometimes gets warm, this does not mean malfunction. The reason is that
the refrigerant gas continuously flows into the indoor unit even while it is not operating.
• When the operation frequency does not go up from lowest frequency.
MXZ-3A30NA MXZ-3A30NA -
1
MXZ-4A36NA
Check of bus-bar voltage
•Check the voltage of power supply.
•Confi rm outdoor unit failure mode
recall function. (Refer to 12-2.2.)
Blink 5 times
Confi rm LED1 indication lamp on
the outdoor electronic control P.C.
board.
Replace the power board.
Blink 9 times
Replace the outdoor elec-
tronic control P.C. board.
Turn OFF power supply before removing P.C. board.
Confi rm LED1 indication lamp
on the outdoor electronic con-
trol P.C. board.
Turn ON power supply. Start
operation.
Blink 6 times
Replace the outdoor elec-
tronic control P.C. board.
Lighting
Replace the outdoor elec-
tronic control P.C. board.
Blink 9 times
Replace the power board.
Confi rm LED1 indication lamp
on the outdoor electronic con-
trol P.C. board.
Turn ON power supply. Start
operation.
Normal
Lighting Lighting