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Home >> Lincoln >> 2012 >> MKZ Hybrid >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (HVAC - Climate Control System - General Information And Diagnostics (Except Hybrid)) >> Diagnosis And Testing >> Climate Control System >> Pinpoint Tests >> Pinpoint Test O: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON >> Normal Operation

Normal Operation

WARNING: This page is about a different variant/trim than selected.

Under normal operation, for Fusion equipped with navigation  and all MKZ  vehicles, when A/C button is pressed, a message is sent from the Front Controls Interface Module (FCIM) over the Medium Speed Controller Area Network (MS-CAN) bus to the HVAC module. The HVAC module then sends an A/C request message over the MS-CAN bus to the Instrument Cluster (IC), then from the IC through the High Speed Controller Area Network (HS-CAN) bus to the PCM.

For all vehicles equipped with navigation  , when MAX A/C is selected on the touch screen, the Audio Control Module (ACM) sends a message over the MS-CAN bus to the HVAC module that MAX A/C has been selected.

For Fusion not equipped with navigation  , when A/C is requested, a message is sent over the MS-CAN bus to the IC, then from the IC through the HS-CAN bus to the PCM.

Ignition voltage is provided to the A/C clutch relay switch through circuit SBB25 (RD). 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 GD121 (BK/YE).

This pinpoint test is intended to diagnose the following: 

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