Service manual

Special Control SiUS28-902_a

21 Function

3. Special Control

3.1 Startup Control

On activation, the following control is performed to lighten the load of the compressor with liquid

refrigerant located at the compressor at startup. Also, the position of the four-way valve is

defined.

3.1.1 Startup Control in Cooling Operation

3.1.2 Startup Control in Heating Operation

Actuator Operation Remarks

Compressor Differential pressure control

Compressor operating frequency

increases by 2 step / 20 sec. until

Pc - Pe>58 psi.

Outdoor unit fan High pressure control

Initial fan speed is set to STEP 0.

1-step increase with Pc>305 psi

1-step decrease with Pc<261 psi

Four-way valve OFF ⎯

Main electronic expansion valve (EV1) 1400 pls ⎯

Subcooling electronic expansion valve

(EV2)

0 pls ⎯

Hot gas bypass valve (SVP) ON ⎯

Receiver gas discharging valve (SVG) OFF ⎯

Ending conditions

• 230 sec.

• Pc - Pe>58 psi

• 45 sec.

Actuator Operation Remarks

Compressor Differential pressure control

Compressor operating frequency

increases by 2 step / 20 sec. until

Pc - Pe>58 psi

Outdoor unit fan STEP 8 ⎯

Four-way valve ON ⎯

Main electronic expansion valve (EV1) 180 pls ⎯