WHY DOES HEAT BLOW OUT COOL.

  • Tiny
  • lawrencpaul
  • 2005 Mercury Marquis
  • 125,000 miles

Turn heat on heat blows out cool air. Defroster blows cool air. No blown fuses. Started car remove cap from radiator turn heat on high let car run to see if heater warms. Heater does not warm and car does not over heat.

Tuesday, October 2nd, 2012 AT 2:10 PM

4 Answers

  • Tiny
  • KHLow2008
  • Expert
  • 41,938 posts

Is this a manual or automatic HVAC system?

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Tuesday, October 2nd, 2012 AT 2:22 PM
  • Tiny
  • Wrenchtech
  • Expert
  • 19,583 posts

With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are both hot, the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.

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Tuesday, October 2nd, 2012 AT 2:33 PM
  • Tiny
  • lawrencpaul
  • Member

Where is the electric motor/acuator and how can I get to it. I hear opening and closing.

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Tuesday, October 2nd, 2012 AT 3:50 PM
  • Tiny
  • Wrenchtech
  • Expert
  • 19,583 posts

The entire dash has to be removed to access it.

http://i1198.photobucket.com/albums/aa448/Wrenchtech/110742819.gif

http://i1198.photobucket.com/albums/aa448/Wrenchtech/113406266.gif

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Tuesday, October 2nd, 2012 AT 4:03 PM

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