Operation Permission/Prohibition Control - Mitsubishi Heavy Industries SRK20ZJX-S Service Manual

1.6 Operation permission/prohibition control

(Refer to the FDTC series by 25 page)
The air conditioner operation is controlled by releasing the jumper wire (J3) on the indoor PCB and inputting the external
signal into the CnT.
Note (1) Please install the separately-sold Interface kit (SC-BIK-E). Remove the jumper wire (J1 or J3) from the Interface kit circuit board.
(1) The operation mode is switched over between Permission and Prohibition by releasing the jumper wire (J3)
on the indoor PCB.
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.
(2) In the case of CnT input ON (Operation permission)
(a) The air conditioner can be operated or stopped by the remote control signal.
(When the "CENTER" mode is set, the operation can be controlled only by the center input.)
(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.
When the jumper wire (J1) is short circuited
The signal (1) above starts the air conditioner.
(Shipping status)
(3) In the case of CnT input OFF (Operation prohibition)
(a) Air-conditioner is unable to control the operation/stop, ect. in accordance with signals from the remote controller signal
wire.
(b) Air-conditioner stops as it changes CnT input ON → OFF.
1.7 External control (remote display)/control of input signal
(Refer to the FDTC series by 25 page)
(1) External control (remote display) output
Following output connectors (CNT) are provided on the printed circuit board of indoor unit.
Note (1) Please install the separately-sold Interface kit (SC-BIK-E). The output connector (CNT) is located on the circuit board of the Interface kit.
• Operation output: Power to engage DC 12V relay (provided by the customer) is outputted during operation.
• Heating output: Power to engage DC 12V relay (provided by the customer) is outputted during the heating operation.
• Compressor OPERATION output: Power to engage DC 12V relay (provided by the customer) is outputted while the
• MALFUNCTION output: When any error occurs, the power to engage DC 12V relay (provided by the customer) is outputted.
(2) Control of input signal
Control of input signal (switch input, timer input) connectors (CNT) are provided on the printed circuit board of indoor unit.
However, when the operation of air conditioner is under the Center Mode, the remote control by CnT is invalid.
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 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)
compressor is operating.
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