Mitsubishi Electric SRK19CIS, Technical Manual

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4.14 Operation permission/prohibition control
The air conditioner operation is controlled by releasing the jumper wire (J3) on the indoor control board and inputting the external signal
into the CnT.
(1) The operation mode is switched over between Permission and Prohibition by releasing the jumper wire (J3)
on the indoor control board.
(2) When the CnT input is set to ON (Operation permission)
(a) The air conditioner can be operated or stopped by the signal from the remote control signal.
(b) When the CnT input is changed from OFF to ON, the air conditioner operation mode is changed depending on the status of
the jumper wire (J1) on the indoor control board.
(c) When the CnT input is set to OFF (Prohibition)
(a) The air conditioner cannot be operated or stopped by the signal from the remote control signal.
(b) The air conditioner operation is stopped when the CnT input is changed from ON to OFF.
When the jumper wire (J3) is short circuited
Normal operation is enable (when shipping)
When CnT input is set to ON, the operation starts and
if the input is set to OFF, the operation stops.
For the CnT and remote control inputs, the input which
is activated later has priority and can start and stop the
operation.
When the jumper wire (J3) is released
Permission / Prohibition mode
When CnT input is set to ON, the operation mode is
changed to permission and if input is set to OFF the
operation is prohibited.
When the jumper wire (J1) is short circuited
The signal (a) above starts the air conditioner.
(Shipping status)
When the jumper wire (J1) is released
When the CnT input is set to ON, the air conditioner
starts operation. After that, the operation of the air
conditioner depends on (a) above. (Local status)
4.15 Protective control function
(1) Frost prevention for indoor heat exchanger (During cooling or dry)
(a) Operating conditions
1) Indoor heat exchanger temperature sensor (detected with Th2) is lower than 2.5ºC.
2) 3 minutes elapsed after the start of operation.
(b) Detail of frost prevention operation
Compressor OFF
Indoor fan Protects the fan tap just before frost prevention control.
Outdoor fan Depending on the stop mode
(c) Reset condition: Indoor heat exchanger temperature sensor (Th2) is higher than 15 ºC.