1995 mercury heater control valve

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  #1  
Old 12-22-12, 08:10 PM
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1995 mercury heater control valve

I do not have any heat in my car . Both heater hoses are hot at fire wall . I think it must be the heater control valve . where is it located and what are any other simptons of this problem ? It is a 1995 mercury marquis . Thanks
 

Last edited by Gunguy45; 12-23-12 at 08:01 AM. Reason: correct title spelling
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  #2  
Old 12-22-12, 08:39 PM
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these dont use heater control valves. they use what is called a blend door motor. if you remove your glove box you might be able to see it. but they cant be replace with out removing the dash. do you hear a clicking noise when you turn it to hot? if so it just bad. if not the motor might just be stuck and you can nurse it to move by tapping on it. 90% of the time they have to be replaced.
 
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Old 12-23-12, 07:12 AM
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When I go from AC to heat I don't hear anything . Does the heater cores plug very often , but if it was pluged both hoses would probably not be hot at the fire wall . Is their a way to bypass to get the water to circulateand ?
 
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Old 12-23-12, 08:11 AM
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No....heater cores don't plug very often.
If the lines going in and out are hot......the core will be hot.

Your car either uses vacuum operated dampers/doors or mechanical/cable connected type.

In the past.....did you notice a low whooshing sound when you changed thru the functions ?
The control for hotter to cooler.....is that real easy to turn or does it feel like there's a cable attached to it ?

My guess is that you have a vacuum controlled damper system and have lost vacuum to the system. Real common problem. Usually a vacuum line under the hood will become disconnected.
 
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Old 12-23-12, 09:29 AM
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When I change from AC to Heat I really can't hear any change in funtions . Maybe the main switch from one to the other is bad on the dash itself .
 
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Old 12-23-12, 09:51 AM
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When I change from AC to Heat I really can't hear any change in funtions
That's now.......how about before you had this problem ?

Like I said earlier.......most of these systems work on vacuum. No vacuum....no change.

If the main switch was bad you wouldn't have any fan operation either.
 
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Old 12-23-12, 02:43 PM
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Just bought the car that way , not sure before that
 
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Old 12-23-12, 08:32 PM
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these do not use vacuum for the temp blend door they use elc motors. they can stop dead with no signs at all. i asked about a clicking noise because they can go bad two ways. a plastic gear breaks and the motor keeps spinning causing a clicking noise, or the motor just goes bad and does not move(bad spot in windings) why i said try tapping on it. a third possible but not likely chance is the door itself has broke but you once again would hear some kind of noise when changing temps.
 
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Old 12-24-12, 09:08 AM
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Last night when I was messing with it I tried to change from def to heat , vent , floor but it would not change off of def , just keeps blowing cold air from out of def . Why wouldn't their be any hot air coming out even though it's not changing functions . Thanks
 
  #10  
Old 12-24-12, 12:08 PM
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well now it sounds like you have a controller issue. but those doors are vacuum motor controlled. the heat is electric motor controlled. both are told what to do by the main hvac controller. how about seeing if its even plugged up. considering you bought it this way.
 
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Old 12-25-12, 11:28 AM
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not really sure waht the hvac controller is . Is that what you see from the face of the dash above the ash tray ? Thanks for all your help . Hopefully i can get this figured out .
 
  #12  
Old 12-25-12, 09:37 PM
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yes thats it. what you use to change the settings.
 
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Old 12-26-12, 05:28 PM
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Ran a jumper tube from vac line on back of plug itself , when I moved the tube to all the other tubes all the doors open and shut like they should . When hooked back up to controller they did not work . The heat must be elec controlled . I guess maybe my controller might be bad .
 
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Old 12-26-12, 05:47 PM
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as long as there is good power and ground going to yet. yes i would say its bad.
 
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Old 12-27-12, 06:16 PM
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Yep , replaced the heater control today all the funtions work and I now have heat . Sure glad I didn't have to pull the dash . Thanks alot for the help Jeff
 
  #16  
Old 12-27-12, 07:40 PM
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cool, thanks for coming back to submit your cure.
 
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