Check Of Hps; Check Of Bus-Bar Voltage; The Other Cases - Mitsubishi Electric MXZ-2B20NA Service Manual

• When the operation frequency does not go up from the lowest frequency.

Check of HPS

MXZ-3B24NA MXZ-3B30NA MXZ-4B36NA MXZ-5B42NA
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.
0 Ω
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 ?
No
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.

Check of bus-bar voltage

MXZ-2B/3B/4B
Blink 5 times
Replace the power board.
Turn ON power supply. Start
operation.
Confi rm LED1 indication lamp
on the electronic control P.C.
board.
Blink 9 times
Replace the electronic con-
trol P.C. board.
Turn OFF power supply before removing P.C. board.
OBH560G
Infinity
Replace the electronic control P.C.
Yes
board/outdoor control P.C. board.
•Check the voltage of power supply.
•Confi rm outdoor unit failure mode
recall function. (Refer to 11-2.2.)
Confi rm LED1 indication lamp on
the outdoor electronic control P.C.
board.
Blink 6 times
Replace the electronic con-
trol P.C. board.
Normal
Lighting
CN681
Replace HPS.
Replace the electronic con-
trol P.C. board.
Turn ON power supply. Start
operation.
Confi rm LED1 indication lamp
on the electronic control P.C.
Lighting
board.
Replace the power board.
74
MXZ-3B/4B MXZ-5B
Outdoor control
Electronic
control P.C. board
P.C. board
Lighting
Blink 9 times