Condensate Pump Motor (Dm) Control (Only Fdtn (P), Fdt, Fdr Models); Defrost Control (Fdc 6 Series Only); 4-Way Valve Control (1 Phase Models Only); Frost Prevention During Cooling (For Indoor Heat Exchanger) - Mitsubishi FDC 6 Series Service Manual

9)

Condensate pump motor (DM) control (Only FDTN (P), FDT, FDR models)

During the cooling or Dehumidifying operation, the condensate pump motor (DM) is synchronized with the start of compressor
operation. If the operation is switched from the operation stop, error stop, thermostat stop and the cooling of defrosting operation
to the fan or heating operation, the drain motor continues to operate for 2 minutes after the switching.
Overflow detection by means of the float switch is always on regardless of the operation mode. If an overflow occurs (or the float
switch is not connected or the wire is broken), the operation is interrupted as the error stop and the drain motor is operated until the
state of float switch is normalized.

10) Defrost control (FDC 6 series only)

Defrost operation is precisely controlled with the defrost thermostat (23DH
a) Defrost starting conditions
Defrost operation will start only when all of following conditions are met.
1) When the compressor operation time accumulated after the start of heating operation exceeds 30 minutes.
2) When the compressor operation time accumulated after the end of defrost operation exceeds 45 minutes.
3) When the defrost thermostat (23DH1) is turned ON (-6˚C)
b) Defrost terminating condition
If the defrost thermostat (23DH2) is turned OFF (12˚C) or 12 minutes after the start of defrost operation, the defrost opera-
tion is canceled and it returns to the heating operation.

11) 4-way valve control (1 phase models only)

In order to maintain the pressure balance after the stop of compressor during cooling, dehumidifying and heating operation. the 4-
way valve is controlled repeatedly as illustrated below.
Compressor
4-way valve

12) Frost prevention during cooling (For indoor heat exchanger)

In order to prevent the frosting during cooling operation, the temperature of indoor unit heat exchanger (detected by Th
checked 9 min, after the compressor operation start and the unit operation.
This cycle is not operated for 9 min. after the resetting of this frost prevention mechanism.
6
ON
(During cooling, heating)
OFF
ON
(During cooling)
OFF
ON
(During heating)
OFF
OFF (52C)
2.5˚C
Indoor heat exchanger (ThI-R)
) and a timer.
1, 2
50 sec.
120 sec.
180 sec. or over
Cooling operation
10˚C
) is
I-R