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No Heat


rooleybob
12-30-2004, 04:25 AM
My 96 Mystique has no heat!!! I live in southern Illinois and it's been pretty damn cold here the last few weeks. The blower works and the thermostat has recently been replaced. I'm guessin that the heater core is shot. Would that be the opinion of every one else??? From what I can see it (the heater core) seems to be right in the middle of the firewall, under the dash. Looks like it will be quite the pain to change, but I hate to pay someone else to do the work. (just spent $1800 replacing my motor)
Anyway, back to my question. What do you all think??? Heater core is bad or could it be something else?? I noticed from my research that there is a heater control valve, but I have no idea where that is or even what it does.
Any suggestions would be appreciated!!! I'm gettin real cold ridin around in this sub-freezing weather with no heat.

Thanks,

FREEZIN' IN ILLINOIS

swiftknight23
01-25-2008, 08:39 PM
first of all, is the ac/ heater even blowing air. if not then it could be a blower, fuse, or electrical problem. but if its blowing air then its most likely the heater core,

this will answer your question on the heater control valve and give you a little background on the heater.

we can understand this diagnosis by understanding how a
standard automotive heater works.
First off, there is the "heater core". It is located behind the
dashboard vents and looks like a mini-radiator. Essentially,
the sole purpose of the heater core is to emit heat. Where
does this heat come from? Well, hot coolant from the
engine is circulated through it. The fan (a.k.a. blower) blows
air through the heater core, out the vents, and thus into the
passenger compartment.
So then, how does the heater control valve fit into all of this?
It controls the flow of coolant to the heater core. If the valve
is open, coolant will flow to the heater core and thus the fan
will blow warm air out the vents. If closed, coolant won't flow.
Hence, the air isn't warm.
It should now be clear that since this vehicle's heater blows
air that isn't warm, the heater control valve must not be
opening. This is either because the valve itself is faulty or
the device activating it is.

hope this helps

Terrell

kmike75
01-26-2008, 06:32 AM
I'm not aware of a valve that sends coolant through the heater core. There is a switch on the control console that activates the heater door control. The door control is located behind the glove box. (You have to remove the glove box to get to it) If the switch on the console is bad, or the door control is bad, the door may not be opening to allow the blower to blow through the heater core and into the cab. I would think that if the core were plugged or coolant wasn't allowed through it, it would cause the car to overheat. Or, the core would fail and you would be asking what people use to clean coolant from their carpets. Coolant has to continue to travel through the system including the heater core otherwise the car will overheat. That's my story and I'm sticking to it.

khaef
01-30-2008, 02:19 AM
RE: No Heat: I have a related problem; on my Mystique V6 1998. Heat will only come out of the "defrost" location, blowing on the windshield, etc. This occurred after I had my car into a Firestone Center to have the Power Steering redone (it leaked and failed-- expensive$$). Before that, I could get heat, and also A.C. in summer from the dash panel and I could switch it to the Defrost area when I needed it. For a long time, I did not notice any heat /cooling blowing on the floor area, but just lived with it. Still, in very cold, wintery Chicago area this winter, I'd really like to have the heat coming out of the front Dash Panel vents-- so I can put my hands on it to warm up a bit when first driving. Your Heat Control Panel door intriques me: Could the guys have knocked it "shut" or otherwise messed it up when they installed the Power Steering in November, an area that is very close to where the Glove Box/ Interior of the car is? That's what I'm thinking because the heat wouldn't deliver from the central (middle location) panels right after I got it back from having the Power Steering repaired.

I took it back to them recently, and they ran a cooling system test-- which it passed of course. I did not realy authorize this-- as we all knew and could check by turning the temperature dial up, and the blower on, that there was warm heat pumping out-- only it only comes out of the one windshield (defrost) area.

What controls the opening/closing of those vents, when you dial different locations on the instrument panel? Is it this door you were referring to-- and does it mean that a new battery/transistor is needed? Trying to get this info before I bring it back to them on Friday. I don't want to have to pay a lot to have them explore this in fact I think they should find the problem and fix it gratis, since it occurred immediately after I got it back from them for the Power Steering repair mentioned above. The guys did not seem to know what to do. A thorough Mercury Mystique Repair manual would problably help out a lot here, but I don't have one. Did not yet go to the Mercury dealer-- even though they may be the ones who "know" what is wrong. Thanks for any advice/help anyone can give.

Kraig
03-02-2008, 01:29 AM
RE: No Heat: I have a related problem; on my Mystique V6 1998. Heat will only come out of the "defrost" location, blowing on the windshield, etc. This occurred after I had my car into a Firestone Center to have the Power Steering redone (it leaked and failed-- expensive$$). Before that, I could get heat, and also A.C. in summer from the dash panel and I could switch it to the Defrost area when I needed it. For a long time, I did not notice any heat /cooling blowing on the floor area, but just lived with it. Still, in very cold, wintery Chicago area this winter, I'd really like to have the heat coming out of the front Dash Panel vents-- so I can put my hands on it to warm up a bit when first driving. Your Heat Control Panel door intriques me: Could the guys have knocked it "shut" or otherwise messed it up when they installed the Power Steering in November, an area that is very close to where the Glove Box/ Interior of the car is? That's what I'm thinking because the heat wouldn't deliver from the central (middle location) panels right after I got it back from having the Power Steering repaired.

I took it back to them recently, and they ran a cooling system test-- which it passed of course. I did not realy authorize this-- as we all knew and could check by turning the temperature dial up, and the blower on, that there was warm heat pumping out-- only it only comes out of the one windshield (defrost) area.

What controls the opening/closing of those vents, when you dial different locations on the instrument panel? Is it this door you were referring to-- and does it mean that a new battery/transistor is needed? Trying to get this info before I bring it back to them on Friday. I don't want to have to pay a lot to have them explore this in fact I think they should find the problem and fix it gratis, since it occurred immediately after I got it back from them for the Power Steering repair mentioned above. The guys did not seem to know what to do. A thorough Mercury Mystique Repair manual would problably help out a lot here, but I don't have one. Did not yet go to the Mercury dealer-- even though they may be the ones who "know" what is wrong. Thanks for any advice/help anyone can give.

I've had the same problem with my '96. The control that works this is under the dash center console that is directly to the right of where you step on the accelerator. Tough to get to, you will need a flash light or equivalent to see even in direct sunlight. Crawl down on the drivers floor board & shine your flashlight about 6" back from the accelerator pedal to the back of the center lower dash assembly. You should see a small aluminum cylinder piece about 2 1/2" in diamater & about an 1 1/2'" in lenght. At the top of this cylinder is a plastic arm that moves up & down from inside the cylinder via a vacuum line. This arm has a hole in the top of it that is supposed to be connected to another plastic arm that goes thru this hole. Release the vacuum line from the cylinder & the arm on top of the cylinder will extend upward so you can reattach the plastic arm thru the hole. Reattach the vacuum line & you're in business again! My daughter use to knock this off all the time with her pointed shoes. I ended up putting a dash of super glue on the plastic piece that extended thru the hole in the one arm so this didn't happen again. Hope this is helpful....

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