Daikin FTK Series Service Manual page 43

Control Specification
3.4.3 Four Way Valve Switching
Outline Heat Pump Only
During the heating operation current must be conducted and during cooling and defrosting
current must not be conducted. In order to eliminate the switching sound (as the four way valve
coil switches from ON to OFF) when the heating is stopped, the delay switch of the four way
valve must be carried out after the operation stopped.
Details The OFF delay of four way valve
Energize the coil for 160 sec after unit operation is stopped.
3.4.4 Four Way Valve Operation Compensation
Outline
Heat Pump Only
At the beginning of the operation as the four way valve is switched, acquire the differential
pressure required for activating the four way valve by having output the operating frequency,
which is more than a certain fixed frequency, for a certain fixed time.
Details Starting Conditions
1. When starting compressor for heating.
2. When the operating mode changes to cooling from heating.
3. When starting compressor for rushing defrosting or resetting.
4. When starting compressor for the first time after the reset with the power is ON.
5. When starting compressor for heating next to the suspension of defrosting.
6. When starting compressor next to the fault of switching over cooling/heating.
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DAMA-SM-21-001
Functions and Control