Air Temperature Control (ATC) Request

Air Temperature Control (ATC) Request
The ATC request comes via the ATC switch located in the facia panel. When the driver operates the switch it acts as a request from the ATC ECU to engage the ATC clutch to drive the system.

During periods of high driver demand such as hard acceleration or maximum rev/min the ATC clutch will be disabled for a short time. This is to reduce the load on the engine.

Input/Output
The operation of the ATC request is via a switch being connected to earth. Voltage is supplied via pin 38 of connector C0637 of the ECM, at the point at when the switch is pressed the connection is made and the ATC clutch is engaged.

The ATC request can fail as follows:
^ Open circuit.
^ Short circuit to voltage supply.
^ Short circuit to vehicle earth.
^ Wiring loom fault.

In the event of an ATC request failure, the ATC system does not work.

Should a malfunction of the component occur the following fault codes may be evident and can be retrieved by TestBook.