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Cadillac Sedan Deville Has No Heat

Q. I have a 1994 Cadillac Sedan Deville, I changed the antifreeze, checked all of the hoses, put in new thermostat and my heater still does not put out warm air, but it is moving freely through the engine what do I need to do now?

Thanks,
Elisabeth

Cadillac Sedan Deville Has No Heat

A. I'm assuming air flow through the Electronic Climate Control (ECC) is normal, the air is just not getting hot.

If that is, indeed, the case, then I believe the problem may be with the Air Mixture Valve. This valve, door actually, directs incoming air either through the heater core to be warmed or around it.

This is controlled by the Air Mixture Valve Control Motor in the Climate Control Center (CCC). You can use the ECC self diagnostics to access the DTC to confirm this, or any other problem.

To enter diagnostic mode, proceed as follows:

  1. Turn ignition "ON."
  2. Depress the "OFF" and "WARMER" buttons on the Climate Control Center (CCC) simultaneously and hold until the segment check appears on the Instrument Panel Cluster (IPC).

TROUBLE CODE DISPLAY:
After entering On-Board Diagnostics, a segment check is automatically performed and then any trouble code stored in computer memory will be displayed. Codes may be stored for the Powertrain Control Module (PCM), Instrument Panel Cluster (IPC), Air Conditioning Programmer (ACP), Supplemental Inflatable Restraint (SIR), Traction Control System (TCS) or Road Sensing Suspension (RSS) systems.

Each trouble code consists of the system abbreviation: (E: Engine, PCM), (I: IPC), (A: ACP), (R: SIR), (T: TCS), (S: RSS), a three digit code identifier, and the letter C or H. All codes for each system are displayed together, in the order of their three digit number (lowest first). The final digit of the code, a "C" or "H" is used to indicate whether the code is Current or History. A "C" means the fault was still present the last time the diagnostic test was run, while "H" means the failure was not present the last time the code was tested for.

If no codes are present for a system, a "NO X CODE" message (with "X" being the system i.e. E, I, A, R, T or S) will be displayed. If the communication line to a component is not operating, a "NO X DATA" message will be displayed, indicating that the IPC could not communicate with that system.

SELECTING THE SYSTEM:
After trouble codes have been displayed, a specific vehicle system PCM, IPC, ACP, SIR, TCS, RSS may be selected for testing.

The first available system will be automatically displayed (i.e. PCM?). While selecting the system to test, any of the following actions may be taken:

  1. Depressing the "HI" button on the CCC will select the displayed system for testing.
  2. Depressing the "LO" button on the CCC will display the next available system selection. This allows the display to be stepped through all system choices. This list of systems can be repeated following the end of the system list.
  3. Depressing the "OFF" button the CCC will stop the system selection process and return the display to the beginning of the trouble code sequence.

SELECTING THE TEST TYPE:
Having selected a system, the first available test type will be displayed (i.e. PCM DATA?, PCM CLEAR CODES?). While selecting a specific test type, any of the following actions may be taken:

  1. Depressing the "HI" button on the CCC will select the displayed test type. At this point the first of several specific tests will appear.
  2. Depressing the "LO" button on the CCC will display the next available test type for the selected system. This allows the display to be stepped through all available test type choices. This list of test types can be repeated following the display of the last test type.
  3. Depressing the "OFF" button on the CCC will stop the test type selection process and return the display to the next available system selection.

CLEAR CODES
Selection of "CLEAR CODES?" test will result in the message "CODES CLEARED" being displayed along with the selected systems name. This message will appear for 3 seconds and then return to the next available test type.

EXITING DIAGNOSTIC MODE:
To get out of the diagnostic mode anytime during the test, depress the "AUTO" or "DEFOG" button, or turn the ignition switch "OFF." Trouble codes are not erased if this is done prior to selecting "CODES CLEARED."

ECC Trouble Code Descriptions:

  • DTC A010
  • - Outside Temperature Sensor Circuit
  • DTC A011
  • - High Side Temperature Sensor Circuit
  • DTC A012
  • - Low Side Temperature Sensor Circuit
  • DTC A013
  • - In-Car Temperature Sensor Circuit
  • DTC A015
  • - Sunload Sensor Circuit
  • DTC A037
  • - Loss of IPC Data
  • DTC A040
  • - Air Mix Valve (Door) Circuit Problem
  • DTC A047
  • - Low Refrigerant Charge
  • DTC A048
  • - Low Refrigerant Pressure
  • DTC A050
  • - HVAC - Coolant Temperature Too High

Additional Information provided courtesy of ALLDATA

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