A/C Engagement

A/C Engagement







A/C request
A number of conditions must be fulfilled in order for the A/C relay to be grounded and for the A/C compressor clutch to begin to draw power.

For control panel with A/C, the function is activated manually. In order for an A/C request to be completed, the fan must be in position 1-4 and the A/C button in the ON position.

For ACC, the A/C request is automatic when the ACC-panel is ON (that is, OFF is not pushed in), ECON is not selected, the engine is running and the outside temperature exceeds +1°C.

The engine management system compensates the engine for the extra load of the compressor.


A/C engagement
1. A/C request comes from the control panel with A/C or ACC.
For control panel with A/C, the signal arrives on a direct lead, and for ACC the information goes on the bus to DICE.
2. The pressure in the condenser must be lower than 27 bar and higher than 2 bar. The pressure sensor senses the pressure in the condenser and sends the information to DICE.
3. The temperature in the evaporator must exceed +4°C. DICE receives the information from the anti-freeze sensor.
4. The engine temperature must be lower than +126°C (petroleum engine) and +118°C (diesel) engine. DICE receives the information from respective engine management system on the bus via MIU.
5. The conditions for A/C request are fulfilled and the engine management system grounds the A/C relay. When the relay is grounded, power is supplied via the compressor temperature monitor. If the temperature monitor has been activated, it is reset automatically.


IMPORTANT: If a trouble code is generated for any of the sensors for above values, the conditions for engagement of the A/C are not fulfilled.