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Home >> Lincoln >> 2009 >> MKX FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1115 (Climate Control System - General Information And Diagnostics) >> Diagnostic Tests >> Climate Control System >> Pinpoint Tests >> Pinpoint Test K: The Air Conditioning (A/C) is Always On >> Normal Operation

Normal Operation

WARNING: This page is about a different car, the 2007 Lincoln MKX and 2007 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

Under normal operation, when A/C is requested, in the electronic automatic temperature control (EATC) module system, a message is sent over the medium speed controller area network (MS-CAN) bus to the instrument cluster, then from the instrument cluster through the high speed controller area network (HS-CAN) bus to the powertrain control module (PCM); or in electronic manual temperature control (EMTC) systems, voltage is sent to the instrument cluster through circuit CH434 (GY/YE), then a message is sent from the instrument cluster through the HSCAN bus to the PCM.

Ignition voltage is provided to the A/C clutch relay switch. When the PCM energizes the relay, ignition voltage is supplied to the A/C clutch through circuit CH401 (VT/WH). Ground is supplied for the A/C clutch through circuit GD120 (BK/GN).

Possible Causes

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