Emergency Operation - Mitsubishi Electric PUHZ-RP8YHA Technical & Service Manual

13-8. EMERGENCY OPERATION

(1) When the error codes shown below are displayed on outdoor unit or microcomputer for wired remote controller or indoor
unit has a failure, but no other problems are found, emergency operation will be available by setting the emergency opera-
tion switch (SWE) to ON and short-circuiting the connector (CN31) on outdoor controller circuit board.
When following abnormalities occur, emergency operation will be available.
Error code Inspected content
U4 Open/short of pipe thermistor (TH3, TH32/TH6)
Indoor/outdoor unit communication error •Signal receiving error (Outdoor unit)
E8
E9 Indoor/outdoor unit communication error •Transmitting error (Indoor unit)
E0 ~ E7 Communication error other than outdoor unit
Ed Communication error between outdoor controller board and M-NET board (Serial communication error)
(2) Check the following items and cautions for emergency operation
1Make sure that there is no abnormality in outdoor unit other than the above abnormalities. (Emergency operation will
not be available when error code other than the above are indicated.)
2For emergency operation, it is necessary to set the emergency operation switch (SWE) on indoor controller circuit board.
Refer to the electrical wiring diagram of indoor unit for how to set the indoor unit.)
3During 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.
4Do 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.
5Do 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
1Turn the main power supply off.
2Turn on the emergency operation switch (SWE) on indoor controller circuit board.
3Set the shorting pins of emergency operation connector (CN31) on outdoor controller circuit board to ON.
4Use SW4-2 on outdoor controller circuit board to set the operation mode (cooling or heating). (SW4-1 is not used.)
5Turning the main power supply on will start the emergency operation.
(4) Releasing emergency operation
1Turn the main power supply off.
2Set the emergency operation switch (SWE) on indoor controller circuit board to OFF.
3Set the shorting pins of emergency operation connector (CN31) on outdoor controller
circuit board to OFF.
4Set SW4-2 on outdoor controller circuit board as shown in the right.
wIf shorting pins are not set on emergency operation connector (CN31), the setting remains OFF.
SW4
Heating
ON
1 2 Cooling
OFF
47
CN31
Shorting pins
ON
SW4
Heating
ON
1 2 Cooling