Emergency Operation; Emergency Operation Procedure; Releasing Emergency Operation - Mitsubishi Electric SUZ-KA24NAHZ Service Manual

10-7. EMERGENCY OPERATION

(1) When any check codes shown below is displayed on outdoor unit, or microprocessor for wired remote controller or indoor
unit has a failure while no other problems are found, emergency operation will be available by setting the emergency opera-
tion switch (SWE) ON and short-circuiting the connector (CN31) on outdoor controller board.
●When following abnormalities occur, emergency operation will be available.
Check code Inspected content
U4 Open/short of thermistor (TH3/TH6/TH7/TH32/TH8)
UE Open of pressure sensor (T
E8 Indoor/outdoor unit communication error •Signal receiving error (Outdoor unit)
E9 Indoor/outdoor unit communication error •Transmitting error (Indoor unit)
E0 – E7 Communication error other than outdoor unit
Ed Communicaiton error between outdoor controller board and M-NET board (Serial communication error)
(2) Check the following items and cautions for emergency operation
1 Make sure that there is no abnormality in outdoor unit other than the above abnormalities. (Emergency operation will
not be available when check codes other than the above are indicated.)
2 For emergency operation, it is necessary to set the emergency operation switch (SWE) on indoor controller board. (Refer
to the electrical wiring diagram of indoor unit for how to set the indoor unit.)
3 During emergency operation, the air-conditioner will continuously be operated by supplying power and stopping it. It can
not be turned on or off by remote control, and temperature control is not possible.
4 Do not perform emergency heating operation for an extended period of time. If the outdoor unit starts defrosting during
this period, cold air will blow out from the indoor unit.
5 Do not perform emergency cooling operation for more than 10 hours. Neglecting this could result in freezing the heat
exchanger in indoor unit.

(3) Emergency operation procedure

1 Turn the main power supply off.
2 Turn on the emergency operation switch (SWE) on indoor controller board.
3 Set the shorting pins of emergency operation connector (CN31) on outdoor controller board to ON.
4 Use SW4-2 on outdoor controller board to set the operation mode (cooling or heating). (SW4-1 is not used.)
5 Turning the main power supply on will start the emergency operation.

(4) Releasing emergency operation

1 Turn the main power supply off.
2 Set the emergency operation switch (SWE) on indoor controller board to OFF.
3 Set the shorting pins of emergency operation connector (CN31) on outdoor controller
board to OFF.
4 Set SW4-2 on outdoor controller board as shown in the right.
Note: If shorting pins are not set on emergency operation connector (CN31), the setting remains OFF.
OCH754A
)
63HS
SW4
CN31
Heating
ON
1 2 Cooling ON
SW4
ON
1 2
55
Shorting pins
OFF
Heating
Cooling