Mitsubishi Electric PLA-A12EA8 Service Manual page 25

9-5. EMERGENCY OPERATION
9-5-1. When wireless remote controller troubles or its battery is exhausted
DEFROST/STAND BY lamp (Orange)
Operation lamp (Green)
Emergency operation switch (heating)
Emergency operation switch (cooling)
Receiver
9-5-2. When wired remote controller or indoor unit microprocessor fails
1.When the wired remote control or the indoor unit microcomputer has failed, but all other components work properly,
setting the switch (SWE) on the indoor controller board ON will begin the indoor unit Emergency Operation.
When Emergency Operation is activated, the indoor unit operates as follows:
(1) Indoor fan is running at high speed. (2) Drain pump is working.
*Note on the wireless remote control: when the remote control does not function, it is possible to activate
Emergency Operation by using the indoor unit emergency operation switch (SW1, SW2 of the wireless signal
receiver board).
However, if the indoor unit microprocessor has failed, it is necessary to proceed with points 2 and 3 below as in the
case of the wired remote control.
2.When activating Emergency Operation of the cooling or heating, set the switch (SWE) on the indoor
controller board and activate Emergency Operation of the outdoor unit.
For details on how to activate Emergency Operation of the outdoor unit, refer to the outdoor unit wiring diagram.
3.Before activating Emergency Operation, check the following points:
(1)Emergency Operation cannot be activated when:
• the outdoor unit malfunctions. • the indoor fan malfunctions.
• it has detected the malfunction of drain pump during self-diagnosing.
(2)Emergency Operation becomes continuous only by switching the power source on/off.
ON/OFF on the remote control or temperature control etc. does not function.
(3)Avoid operating for a long time when the outdoor unit begins defrosting while Emergency Operation
of the heating is activated because it will start to blow cold air.
(4)Emergency cooling should be limited to 10 hours maximum (The indoor unit heat exchanger may freeze).
(5)After Emergency Operation has been deactivated, set the switches, etc. to their original positions.
(6)Movement of the vanes does not work in Emergency Operation, therefore slowly set them
manually to the appropriate position.
TCH120A
When the remote controller cannot be used
When the batteries of the remote controller run out or the remote control-
ler malfunctions, the emergency operation can be done using the emer-
gency buttons on the grille.
Starting operation
• To operate the cooling mode, press the
seconds .
• To operate the heating mode, press the
seconds .
Note: Lighting of the Operation lamp
Details of emergency mode are as shown below.
Operation mode
Set temperature
Fan speed
Airflow direction
Stopping operation
• To stop operation, press the
25
for more than 2
button
for more than 2
button
means the start of operation.
COOL HEAT
75°F [24°C] 75°F [24°C]
High High
Horizontal Downward 5
button or the button .