Mitsubishi Heavy Industries FDC508HES3 Owner's Manual download pdf (Page 15)

Outdoor air temperature (°C)

Outdoor fan

operates

at Hi speed

Outdoor fan

stopped

2) Control of fan for outdoor unit for de-icing

If DIP switch SW5-2 on the printed circuit board for the outdoor unit is set to on, the

fan on the outdoor unit which has been stopped will operate for 10 seconds at Hi speed

every 10 minutes when the outdoor air temperature is 3 °C or less.

-20

-15

-10

-5

-15 -10 -5

Outdoor air temperature (°C) [Th

-A]

Heat exchanger temperature

(°C)

[Th

-R]

0510

Zone for initiate temp. of defrost

Initiation temp. of defrosting

Note (1) If DIP switch SW5-1 on the printed circuit board for the outdoor unit is set to on, defrost operation will begin when temperature of the heat

exchanger for the outdoor unit reaches -7 °C.

a) Defrost Operation

Switching of the control of the 4-way selector valve during defrost operation can be performed by enabling/disabling the

jumper wire (J17) on the printed circuit board for the outdoor unit.

(i) J17 None (4-way selector valve ON during heater operation)

Defrost operation is performed with the compressor on, the fan for the outdoor unit off and the 4-way selector valve off.

(ii) J17 With (4-way selector valve OFF during heater operation)

Defrost operation is performed with the compressor on, the fan for the outdoor unit off and the 4-way selector valve on.

b) Defrost finished

(i) Once defrost operation has started, it will finish after the cumulative operating time of the compressor has reached 12

minutes (factory setting: SW5-1 OFF).

Note (1) This time will become 14 minutes if the DIP switch (SW5-1) on the printed circuit board on the outdoor unit is set to on.

(ii) Switching of the defrost recovery time can be performed by enabling/disabling the jumper wire (J18) on the printed

circuit board for the outdoor unit.

J18 (SW6-2) With: 14 °C, J18 (SW6-2) None: 18 °C

Defrost control

Defrost operation will start when the temperature of the heat exchanger for the outdoor unit (Tho-R detection) and the outdoor air

temperature (Tho-A detection) enter the start of defrost range shown in the figure below.

Initiation temp. of defrosting (Detected by Tho-R, Tho-A)

SV -close

SV -open

Discharge gas temp (°C)

115108

3) Discharge temperature control during cooling/heating (Only case of FDC(P)208~508 type)

As the discharge gas temperature (detected with Th

O-D) rises during cooling/heating operation, the capillary bypass and the liquid

bypass solenoid valve (SV1) are opened so that the abnormal rise of discharge gas temperature is prevented.

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Mitsubishi Heavy Industries FDC508HES3 Owner's Manual Page 15

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