Electronic Expansion Valve Control; Drain Pump Operation; Special Control; Room Temperature Control - Fujitsu Airstage VR-II Series Service Manual

3-4 ELECTRONIC EXPANSION VALVE CONTROL

1. Initialization
When the power is turned ON.
When it has passed the limited time since the last initialization.
2. Operation Control
When indoor unit stopping by Thermo-OFF condition.
Outdoor unit Condition
OFF
Cooling
Heating
When starting up
(Cooling) Move to the cooling control base pulse in steps.
(Heating) Move to the heating control base pulse in steps.
Automatic operatic control
Automatic PI control is performed based on the indoor unit heat exchanger outlet temp and inlet temp.

Room temperature control

The room temperature is controlled so that it reaches to the set-up temperature based on the difference
between the room temperature and the set-up temperature, and the change of indoor unit temperature.
Cooling operation: if the room temperature becomes 0.5 C lower than the set-up temperature, EEV is fully closed.
Heating operation: if the room temperature becomes 0.5 C Higher than the set-up temperature, EEV is slightly opened.

3. Special Control

Oil recovery operation
Test run operation
Freeze prevention control : Fully closed.
Vacuuming operation
Defrost operation

3-5 DRAIN PUMP OPERATION

(1) When cooling and refrigerant circulation starts, the drain pump starts simultaneously.
(2) The drain pump operates continuously for 3 minutes after the refrigerant circulation stopped.
(3) When the refrigent circulation is stopped by a start of indoor heat exchanger frost prevention
operation, the drain pump will turn off in 1 hour after the end of indoor heat exchanger frost
prevention operation.
(4) When the water level in the drain pan rises up and then the float switch functions:
1 Microcomputer stops the refrigerant circulation and indoor fan motor operation.
2 Drain pump operates continuously for 3 minutes after the float switch is turned off.
(Almost condensing water may be drained)
(5) When the float switch turns ON continuously for 3 minutes, 'FAILURE INDICATION' operates.
(6) When the float switch turns OFF within 3 minutes, the unit starts cooling operation.
EEV Condition
Fully closed
Fully closed
Slightly open
*In case of protection controlling, EEV keeps open position.
: Controlled pulse(Maximum 1400 puls)
: Controlled pulse.
: Fully open.
: Controlled pulse(Maximum 1400 puls)
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