Question about 2004 Pontiac Grand Prix

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2004 pontiac gran prix gt

Will not blow hot air if the fan is turned down low it will blow some warm air but when you turn it up full blast it blows cold air i changed the thermostAT BUT IT DIDNT help

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  • bob nickerson Nov 04, 2008

    thanks for responding the blower works fine it just blows cold air when turned up to hi does this still sound like the blower moter resister if so how hard is it to replace and do you know what one would cost

    thanks bob

  • bob nickerson Nov 04, 2008

    water level is ok it just blows warm air when the fan is turned to low but when i turn it to hi it blows cool air

  • bob nickerson Nov 06, 2008

    my sticker on the door says 03/04 could this still be the problem it sure sounds like whats happening

    when you say instament pnl are you talking aboubt the dash board if so how do you pop it off

    i think your really close to helping me

    thanks again bob

  • butch welch May 11, 2010

    Have you checked your water level. The water can be just low enough to not effect the engine but can effect the heat. Lets start with that then move on to other idea.



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I would suggest replacing the blower motor resistor. When this component fails the blower will only work on one spped or none. This is a very common issue with all automotive models

Posted on Nov 04, 2008

  • Brian032472
    Brian032472 Nov 04, 2008

    there is a TSB for this Item.

    Early production 2004 Grand Prix vehicles built in February and early March 2003 were produced with a white film material on the mode valve that may stick when the blower motor is operating at high speed. This concern can be easily diagnosed by operating the HVAC system at the highest blower speed and then cycling through all of the HVAC air delivery modes and checking to see if the air flow comes out of the correct air outlets. If the mode valve is sticking and not allowing the air to come out of the correct air outlet, try lowering the blower speed 50% and then recheck the airflow. If the air flow is now coming out the correct outlet for the selected mode, then the mode valve is intermittently sticking at high blower speeds.

    A new mode valve went into production in early March 2003. The film on the original mode valve was white. The film on the new mode valve is orange on the inside and black on the outside. To identify an early built vehicle, inspect the build sticker on the driver's doorjamb and look for the build date. If the vehicle has a build date of February or March 2003, then the HVAC module must be inspected to determine the module part number.

    To inspect the HVAC module, open the instrument panel compartment and then rotate it completely out of the opening in the instrument panel. To remove the glove box door arm, you must squeeze the upper and lower portion of the plastic arm using your thumb and fore finger near the IP opening end. Inspect the right side of the HVAC module and locate the white barcode identification label at the lower right of the air inlet assembly. The HVAC module part number is found in the first string of digits immediately below the DELPHI name in the upper left corner of the label. If the HVAC module part number is either 10335274 or 10343400, a new mode valve, P/N 10325510, must be installed. Three evaporator case screws, P/N 52466167 (sold individually), are also required to complete this repair. Follow the Mode Valve Assembly Replacement procedure in the HVAC section of SI. If a new design mode valve is already installed and the mode change concern at high blower speed is still present, then refer to the Diagnostic Starting Point - Heating, Ventilation and Air Conditioning procedure.



Damn Brian, your technical and I mean that in a good way..Try all of the different positions on the control, just see if it goes to vent, floor, defrost, do this in low and high fan. May even want to touch the hoses to see if you have hot water going and coming to the heater

Posted on Nov 04, 2008


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