2001 Mercury Marquis A/C / Heater unit

2001 MERCURY MARQUIS
75,000 MILES • V8 • 2WD • AUTOMATIC
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MUDDYWATER
  • MEMBER
  • 2 POSTS
My A/C has a auto mode where you set the temp and it keeps it there by using both ac and heat. The other day It was very cold, my temp was set to 80. I heard what sounded like a solenoid valve or switch clicking a couple of times and the heat started when the engine warmed up. Problem, the heat kept comming out, when i turned it down it switched from floor to dash vents but was still hot, switched the system over to max ac it was still blowing hot, but the ac was working as well. all systems switch as programmed, I.E. Defroster blows out top of dash floor blows floor ac blows out vents, its just all heat all the time and the ac still comes on but is negated by the heat. My guess is some kind of door that closes off the heat but is now stuck open. any help or suggestions
Dec 12, 2007 at 8:07 PM
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FLEXY5
  • CAR REPAIR CONTRIBUTOR
  • 512 POSTS
The door that does block off the heat is called the blend door. There is a small motor (blend door actuator) mounted on the top of the plenum case. You have to remove the dash to replace it, but you can see it with the glove box pulled down. It's made of plastic and the clicking noise you hear are the plastic teeth that are broken.
Dec 12, 2007 at 10:00 PM
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