Fedders R407C Service Manual page 54

V. Modes of Operation
1. Cool Mode
The air-con controller lowers the room temperature in this mode.
In cool mode, the indoor fan is always turned on, allowing it to run at the set speed.
To stop the cool mode cycle, the compressor, outdoor fan are turned off, the 4-way valve
which serves no function in this mode is still kept at off. The indoor fan is however allowed
to continue running at set speed.
The controller monitors room temperature and compares it against set/desired temperature. It
starts and stops the cool mode cycle according to the following rules:
Room Temperature < Set pt-1°C = Set pt-1°C
Cool Mode Cycle
* Maintain current state
If room temperature
fan runs according to following table:
ID Room Temp., Tr
ID Fan
* Maintain current state
2. Dry Mode
Dry mode operation extracts moisture from the indoor air and tries to maintain room
temperature to the default set temperature of 22 C.
To dry the air, the controller executes the dry mode cycle, which toggles the compressor and
outdoor fan on for 10 minutes and off for 5 minutes repetitively.
The temperature setting, which is not changeable by user, is internally set at 22°C.
In this mode, the indoor fan constantly runs at the low speed. The 4-way valve that serves no
function in this mode is always kept OFF.
Room Temperature <Set pt-1°C
Dry Mode Cycle
Pre-dry : compressor on, outdoor fan on and 4-way valve kept off.
* Maintain current state
3. Heat Mode (applicable on Heat Pump Unit only)
Heat mode operation can be chosen if it is desired to raise the room temperature. In this
mode, the air-con controller turns on the compressor, outdoor fan, 4-way valve and indoor
fan to provide the heating effect. The above operation, when executed in accordance to the
device protection criteria and cool fan prevention requirement is termed the heat mode
cycle.To stop heat mode cycle, the compressor and outdoor fan are turned off.
Stop Stop
16 C, compressor, outdoor fan and 4-way valve turn off. The indoor
Tr<=15 C 15 C<Tr<16 C
LOW
Set pt-1 °C
Start Start
= Set pt. = Set pt+1°C
*
Tr>=16 C
* SET
Set pt. Set pt+1°C
*
> Set pt+1°C
Start Start
>Set pt+1°C
Pre-dry Pre-dry
F7