Heat issues with HVAC - 2001 Deville
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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, Heat issues with HVAC - 2001 Deville in Past Cadillac Vehicle Discussion; On my 2001 deville at low rpms the heat blows cold but as soon as I start revving the car ...
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    cfix85 is offline Cadillac Owners Member
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    Heat issues with HVAC - 2001 Deville

    On my 2001 deville at low rpms the heat blows cold but as soon as I start revving the car it blows hot again I'm thinking there's air in the heater core but how do I get it out

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    Submariner409's Avatar
    Submariner409 is online now If it won't run, slap in a big stereo
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    Re: Heat issues with HVAC - 2001 Deville

    Your cooling system is self-purging. Attached to the top side of the coolant reservoir is a black hose/pipe that runs over across the engine to a hollow bolt/nipple on the water crossover/water pump area - driver's end of the engine. If that purge line clogs, it builds up air/gases in the coolant, and they normally block heater core flow.

    The normal coolant level in that reservoir is half full, cold. So, with the engine cold, remove the reservoir cap and also the rubber purge line hose at the reservoir side. Hold the purge hose in the open reservoir neck and have an assistant start the engine normally. There should be a steady flow - not river - out into the reservoir. if not, shut down and remove the entire purge line and attempt to clean it out, as well as use a drill bit, twisted by hand, in the metal bolt/nipple. That nipple should be clear to a depth of 2.5" or so. If the purge line will NOT clean out it can be replaced with a length of proper sized braid-reinforced fuel line and 2 band clamps from any parts store. Be careful with the reservoir plastic nipple - that gets brittle over time/heat.

    If that won't do it, perhaps a total coolant exchange is in order. If you don't feel qualified to do the work, look at a GM dealer's "coolant exchange" package. Matter of fact, you could go for the entire "fluids exchange" package - coolant, brake fluid, transmission fluid, power steering fluid. It's all recommended periodic maintenance. Probably run you about $400. Cheap term insurance.

  4. #3
    cfix85 is offline Cadillac Owners Member
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    Re: Heat issues with HVAC - 2001 Deville

    i took the purge line off from the surge tank yesterday and it was flowing out i read somewhere that said rev the engine up to 3 to 4 thousand to let it self purge itself

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    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: Heat issues with HVAC - 2001 Deville

    Might also check the belt tensioner to be sure that the WP drive belt is not slipping.

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    Quote Originally Posted by cfix85 View Post
    i took the purge line off from the surge tank yesterday and it was flowing out i read somewhere that said rev the engine up to 3 to 4 thousand to let it self purge itself
    That's after a coolant change.

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    cfix85 is offline Cadillac Owners Member
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    Re: Heat issues with HVAC - 2001 Deville

    how do i go about doing that the person i bought it from told me he just put a new water pump on it

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    does the color coolant have anything to do with it it calls for the red i believe but i noticed it has the green

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    Ranger's Avatar
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    Re: Heat issues with HVAC - 2001 Deville

    If it has a new WP, I would suspect that the tensioner was checked and is OK, but it can't hurt to have a look at it. Just look under the black belt cover on the drivers side and see if the belt is moving at idle (lower left in the picture). Coolant color is irrelevant.

    Courtesy of Submariner409. This is a Seville so there will be some differences, but the basics are the same.

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