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Home >> Chrysler >> 2009 >> 300 Signature Series >> Repair and Diagnosis >> External Pages >> Different car >> Section 248 ((HVAC Systems - Electrical Diagnostics)) >> HVAC - Electrical Diagnostics >> DTC Troubleshooting >> DTC 73: Ac Request Output Signal Too High (MTC) >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2008 Dodge Magnum, 2008 Dodge Charger, and 2008 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK (C105) HVAC MUX CONTROL CIRCUIT VOLTAGE AT A/C HEATER CONTROL C1 HARNESS CONNECTOR 
    Fig 1: Measuring Voltage Of HVAC MUX Control Circuit
    GC0028220Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the A/C Heater Control C1 harness connector.

    Turn the ignition on.

    Measure the voltage of the (C105) HVAC MUX Control circuit.

    Is the voltage above 5.2 volts? 

    Yes 

    1. Go To step  2.

    No 

    1. Replace the A/C Heater Control in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  2. CHECK (C105) HVAC MUX CONTROL CIRCUIT FOR A SHORT TO VOLTAGE 
    Fig 2: Measuring Voltage Of HVAC MUX Control Circuit
    GC0028220Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the Instrument Cluster C2 harness connector.

    Turn the ignition on.

    Measure the voltage of the (C105) HVAC MUX Control circuit.

    Is the voltage above 0.2 volts? 

    Yes 

    1. Repair the (C105) HVAC MUX Control circuit for a short to voltage.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Replace the Instrument Cluster (CCN) in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .