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Ron
Ron, ASE Certified Technician
Category: Mercury
Satisfied Customers: 35826
Experience:  ASE Certs and Ford Certs
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I have a 2002 Mercury Sable GS with heating problems, the air

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I have a 2002 Mercury Sable GS with heating problems, the air won't get hot enough to clear my windshield in a cold morning. I had already replace the thermostat and did the flush. it seems an electrical, sensor problem. My car has the manuals controls. it sounds like a confusion between the cold and hot air switch/sensor. When the compressor is on the air gets like warn, when I disable the compresor the air seems more normal, it's hotter.
the heater core is not leaking either and it seems working fine, both hoses the in and out get hot.

Anyone has any ideas, what could be causing this.

Thank you
John

-Jello jcbo723,

 

Can you tell me if both heater hose are hot going into the Firewall ?

Customer: replied 7 years ago.
Yes they both get hot

-OK then the common cause for the issue you are having is in most cases a bad blend door acuator and replacement in most case will correct your problem . Enclosed are instructions. Its located just under the glove box.

 

graphicgraphic

Customer: replied 7 years ago.

Ron,

You might be in the right track, I will check that rigth now and let you know in an hour or so.

Just to give you one more hint, the manual heating control has three different knobs. one for the fan speed, one for the temperature control and one for the Mode selector control. according with the owners manual it says that if I used the mode selector control for the front panels or the floor registers only the compressor won't run. I did the experiment using only this two positions and it seems the air gets hotter than when I used the windshield mode.

Did you stil think is the blend door acuator, if that is the case. where I can't get this part.It looks a hard part to find.

 

let me know

 

John

The blend door acuator is for temp control and is electronically controlled. Its very common . Remove it and rotate the temp control knob and if its working, you will see it move.
Customer: replied 7 years ago.

Ok, I will work on that right now.

I will get back with you

 

Thank you

John

Ok John, I will be here.
Customer: replied 7 years ago.

Ron,

Do you have a more detail graphics I can use.

My car doesn't match exactly the ones you sent.

my car is a 2002 mercury sable GS.

If you do I will greatly appreciated

 

thank you

John

That is what I sent but here it is right from Mercury

DOWNLOAD HERE

Customer: replied 7 years ago.

Ron,

Thanks for you quick replied and for the new link to get more details.

Well I just removed the door actuator and it's working when I change the control from hot to cold and viceversa. I will check the door and other mechanism to see if I see any defects.

Any other ideas let me know

 

John

OK if it moving then it usually the door.
Customer: replied 7 years ago.

Ron,

I just finished checking the door and other mechanism and all seems fine. is there a sensor that tells the compressor when to work or when not to work. I removed the relay for the AC clutch and it seems the defrost for the windshield the air gets hotter like that, working without the compressor.

 

Any other ideas

 

John

No there isnt a sensor , the temputure is mixed at the blend door. There really is no way of know if its closing unless you tear it down, shuting the clutch down simply turns the AC off and of course the heat should get hotter.

Customer: replied 7 years ago.

So, you are still thinking is the door?

Do you have any schematic in how to tear down the complete system.

it seems harder to do that, I can do it I just don't want to removed things I don't need it.

 

let me know and thanks or all your help

 

John

 

Yes I am thinking the door and yes its not an easy job. The heater core case has to come out and to do this the instrument panel does as well.

 

DOWNLOAD HERE

DOWNLOAD HERE



Edited by Ron on 10/21/2009 at 7:29 PM EST
Customer: replied 7 years ago.

Hello Ron,

Sorry for the delay in reply back. I went to pick up my daughter at her school and guess what, the car didn't start when I was ready to comeback home. I had to call a friend of mine to help me with the problem and we found the problem was with the starter motor.

So we had to go and get the replacement part and fix the problem.

ok, after almost 3 hours I'am back home, to continue with the heating problem.

I got the links you sent for the squematics to removed the unit. Right now is kind of late, is about 6:20 pm over here so I will look over the documents you sent and I will get with you tomorrow, I want to make sure this is something I want to do.

Don't worry I will accept the solution as soon we fix this problem.

 

Thank you

John

Not to worry, I may not be here till later tomarrow as I have a family issue to deal with in the AM but if you need me, leave a message. I will get back ASAP. I will be here all day On Friday as well. It is a big job.
Customer: replied 7 years ago.

Ok ,

Thank you very much,

I will keep you in the loop.

 

Thanks again

 

John

Have a good evening John...
Ron and 7 other Mercury Specialists are ready to help you
Customer: replied 7 years ago.

Hello Ron,

I had decided to keep the car as it's. To check the blend door it seems a lot of work and I don't want to created other problems either. Next spring I will probably get another car. So far with the new thermostat and the new reservoir tank the heat is getting warmer.

If it gets to cold I will just disable the compressor clutch.

I just want to thank you for all the guidance you did and for going the extra mile with me.

 

Best regards

 

John

Your very welcome.