E6021 FUNCTIONAL DESCRIPTION OF COMPRESSOR ENGAGEMENT

Operational Description

The compressor activation circuit is controlled by relay T05, contained in engine bay junction unit B001. This is supplied directly by a line from the battery that enters at pin 1 of control unit connector F and is protected by fuse F19, located in the control unit.During engine start-up, control unit M010 of connector A pin 13 excites relay T09 to provide it with an earth signal. The relay receives power directly from the battery protected by fuse F18. Relay T05 is supplied in turn and excited by engine control unit M010, connector A pin 18, when compressor activation is required.The compressor actiation request comes from climate control unit M070 - pin 4. The signal firstly reaches electronic thermostat N086 and then antifrost thermostat K160. Engine control unit M010 processes signal from both frost thermostats and multistage pressure switch K010. If the pressure and temperature readings from the air conditioning system are correct, the control unit excites relay T05 via pin 18 of connector A to supply compressor L020.Climate control unit M070 receives a power supply via the ignition and direct from the battery. The former is protected by fuse F31 hosed in underfacia junction unit B002 and the latter is protected by fuse F34 housed in optional junction unit B101. The climate control unit contains its own internal lighting that comes on when the side lights are on.

When there is a request to switch on the compressor, the engine management control unit M010 supplies the relay coil T09 housed in the engine compartment junction unit B001 from pin F3 connector C; the relay is energized when control unit M010 sends an earth signal to pin A4 connector B. The supply from the relay T09 is direct from the battery and is supplied to relay T05 and relay J021.When energized, relay T05 supplies relay J020; the latter is operated by the engine management control unit M010 (pin D3 connector A). When energized, it closes its internal contact, supplying compressor L020.Relay J021 guarantees the connection to earth C040 for the relay coil J020 (pin 1). Pin 3 receives a supply from the line protected by fuse F17; when the control unit M010 sends an earth signal, from pin C3 connector A, the relay disconnects the earth at relay J020 and, as a result, the compressor L020 no longer receives a supply.