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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 106 (HVAC Climate Control System - General Information & Diagnostics) >> Diagnostic Tests >> Climate Control System >> Pinpoint Tests >> Pinpoint Test J: The Air Conditioning (A/C) is Always On >> Normal Operation

Normal Operation

WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

Under normal operation, when A/C is requested, the climate control assembly or HVAC module sends voltage to the A/C cycling switch through circuit 348 (RD/VT). The PCM receives input from the A/C cycling switch through circuit 883 (PK/LB). Voltage is supplied to the climate control assembly through circuit 1040 (RD/BK).

Ignition voltage for the A/C clutch relay switch is provided through circuit 1810 (LG/OG). When the PCM receives voltage from the cycling switch and the A/C pressure transducer does not indicate excessive pressure, the PCM provides a ground for the A/C clutch relay. When the relay is energized, ignition voltage is supplied from the A/C clutch relay to the A/C clutch solenoid through circuit 321 (GY/WH). Ground is supplied for the A/C clutch through circuit 57 (BK).

This pinpoint test is intended to diagnose the following:

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