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Engaging the A/C

Engaging the A/C


A/C request

A number of conditions must be met before the A/C relay is grounded and the A/C compressor clutch engages.

For an A/C request to occur, the fan must be in position 1-4 with the A/C button ON.

For ACC, the A/C request is automatic when the ACC panel is on (that is, OFF is not pressed in), ECON is not selected and the outside temperature exceeds 5°C.

Engaging the A/C


1. The A/C request comes from ACC.

The ACC information goes on the bus.

2. Engine temperature must be below 125°C. DICE receives this information from the relevant engine control module on the bus.

3. The condenser pressure must be below 27 bar and higher than 1.75 bar. The pressure sensor detects the condenser pressure.

4. The evaporator temperature must comply with the following conditions:

4.a. If the temperature in the evaporator is above 2°C, DICE sends information regarding the A/C request to the relevant engine control module point 7.

4.b. If the evaporator temperature is below 1°C, the A/C compressor electromagnetic clutch will be supplied with voltage only if points 5 and 6 are fulfilled.

5. The outside temperature must be above 25°C. This information comes from the SID.

6. One of the following conditions must be fulfilled:

6.a. The engine must have been running for less than 30 minutes.

6.b. The speed must be below 5 km/h.

7. Conditions are fulfilled for the A/C request and the relevant engine control module grounds the A/C relay provided that the engine is running. When the relay is grounded, voltage is fed via the overheating protection to the electromagnetic clutch of the compressor. The overheating protection is built into the electromagnetic clutch. If the overheating protection is triggered, the electromagnetic clutch must be replaced.


Important

If any diagnostic trouble codes are generated for any of the sensors at the values above, the conditions for engaging the A/C will not be fulfilled.