Less Time Delay

OPERATION

Compressor 170 and Radiator Fan Motor 37
The AC can be switched on and off by means of AC switch 169, which is supplied from fuse 6, via 29-pole black connector H29-3 or 33-pole blue connector H33-3. When the switch is depressed, the lamp built into the button will be supplied directly (not via the resistor), so it will light up with full intensity. (When the switch is not activated, the lamp is supplied via fuse 6.)

Compressor 170 and ordinary radiator fan are connected via relay 156. The relay will be energized when the following conditions have been satisfied:

- Pressure switch 166 is closed, i.e. the refrigerant pressure is at least 2.8 bar.

- Anti-freeze thermostat (cycling clutch contact) 171 is closed, i.e. the ambient temperature is at least about +6 ±C.

Pin 21 of control unit 200 will then be energized. Relay 156 will be energized when it is earthed via pin 36 of the control unit. When the relay is energized, the compressor will be supplied only if temperature switch 168 is closed. (The switch will open if the engine temperature should exceed about +155 ±C.) Diode 173, which is connected in parallel with the compressor, reduces the voltage transients at the instant when the compressor is switched off.

Delay and Idling Speed Compensation
The delay and idling speed compensation when the AC is switched in are controlled by control unit 200.

AC Radiator Fan 172
Extra radiator fan 172 for the AC is connected via relay 155 and is supplied from fuse 6. The relay coil is suppled from pressure switch 166. The AC radiator fan thus runs when AC switch 169 is depressed and pressure switch 166 is closed.

Recirculation Valve 38
Recirculation valve 38, which controls the recirculation damper, will be switched on when recirculation switch 143 is depressed. The switch is supplied from fuse 6. When the switch is depressed, the lamp built into it will light up with full intensity.