Pump-Down Control; Base Heater On/Off Output Control (Option) - Mitsubishi Heavy Industries V Multi FDC71VNX Technical Manual

(9) Pump-down control

When SW7-1 is OFF, turning ON the pump-down switch SW1 for 2 seconds during the operation stop or anomalous stop
(excluding the thermostat OFF), the pump-down operation is performed. (This is invalid when the indoor unit is operating.
This is effective even when the indoor unit is stopped by the anomalous stop or the power source is turned OFF.)
(a) Control contents
i) Close the service valve at the liquid side. (It is left open at the gas side.)
ii) Compressor is started with the target speed (frequency) at 55 rps in the cooling mode.
iii) Red and green lamps (LED) flash continuously on the outdoor unit control PCB.
iv) Each of protection and error detection controls, excluding the low pressure control, anti-frost control and dewing
prevention control, is effective.
v) Outdoor unit fan is controlled as usual.
vi) Electronic expansion valve is fully opened.
(b) Ending conditions
Stop control is initiated depending on any of the following conditions.
i) Suction pipe temperature of -36°C or lower is detected for 5 seconds continuously.
a) Red LED: Light, Green LED: Flashing, Remote control: Displays stop.
b) It is possible to restart when the suction pipe temperature of -36°C or higher.
c) Electronic expansion valve (cooling/heating) is kept fully open.
ii) Stop by the error detection control
a) Red LED: Flashing, Green LED: Flashing
b) Restart is prohibited. To return to normal operation, reset the power source.
c) Electronic expansion valve (cooling/heating) is left fully open.
iii) When the cumulative operation time of compressor under the pump-down control becomes 5 minutes.
a) Red LED: OFF, Green LED: Flashing, Remote control: Stop
b) It is possible to pump-down again.
c) Electronic expansion valve (cooling/heating) is left fully open.
Note (1) After the stop of compressor, close the service valve at the gas side.
Caution: Since pressing the pump-down switch cancels communications with the indoor unit, the indoor unit and the
remote control display "Transmission error – E5". This is normal.

(10) Base heater ON/OFF output control (Option)

(a) Base heater ON conditions
When all of following conditions are satisfied, the base heater is turned ON.
・ When power source is turned ON
・ During the compressor stop and when "heater OFF condition" indicated in the following (c) isn't formed
・ For 5 minutes from the compressor start
But, when the compressor ON condition is formed and when it's heater OFF by the following (c) item, the heater isn't
tured ON.
・ During defrost operation
(b) Base heater OFF conditions
When all of following conditions are satisfied, the base heater is turned OFF.
・ When it has passed for 5 minutes or more from the compressor start
・ After it passed for 5 minutes from defrost operation return
・ When "heater OFF condition" indicated in the following (c) is formed
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'19 • PAC-T-327