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1993 Sedan DeVille
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6 Posts
Discussion Starter #1
Anybody have any idea where it is??? The blower works but no hot air comes out of the heater. I live in Bend, OR. and even though winter is on its way out, it still gets a might nippy at night!
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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87,115 Posts
There is no heater control valve. That was a valve that was in the heater core supply line and controlled the amount of coolant flow to control temperature. They have not been used in years. Your car has a "T" fitting in the line. If that T has been removed or replaced it must be replaced with the restrictor in the same leg it was removed on or you won't have any heat. If that is not the problem, then it might be a clogged heater core or a failing air mix door actuator.
 

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1993 Sedan DeVille
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6 Posts
Discussion Starter #3
The t fitting is still in the line. Where is the air mix door actuator? Is there any way to test the core without removal? I purchased a Chiltons and ended up returning it because it failed to provide any problem solving tips. In fact the heating system was summed up in a page without any diagrams.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
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87,115 Posts
Get a FSM by Helm Inc. Anything else is useless.

Feel the heater hoses. If one is hot and the other is cold, then the core is plugged.

Air mix door is under the dash on the passengers side I believe.
 

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93 Sedan Deville 4.9L
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1,005 Posts
blend door can be seen by pulling the glovebox out which is easy. Just remove the 4 or so screws inside it and the couple on the face and it slides out in one piece. run the temp between 60 and 90 and you should see the door move. then as suggested make sure the t-fitting has the restrictor on it. Should have an arrow on top pointing toward the passenger side. If you have no luck I have a heater diagnostic page I got elsewhere on the forum that I may be able to dig up.
 

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1993 Sedan DeVille
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6 Posts
Discussion Starter #6
Thank you kindly, I will see if I can tackle the issue.. 20 degrees and no heater is not plesant.
 

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93 Sedan DeVille
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1 Posts
Sorry to bump an old thread, but I have a question regarding the Tee in the coolant hose line behind the motor.

I have a 93 Sedan DeVille with heat on the passengers side floor and dash vents, but little/no heat on the drivers side. I checked the Tee for the coolant line and I had a rather generic looking Tee with no restrictor, so I got a coolant control valve from O reillys. 74799.jpg

I believe the heat has improved, but I am still only getting heat on the passengers side. I have the arrow of the new Tee facing towards the passenger side. (EDIT: Clarification, the restrictor is towards the passenger side.) Could my heater core be partially clogged, the tee on backwards, an actuator under the dash not functioning properly, or should I put the old Tee back on?
 

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1993 Coupe Deville, 2009 XLR-V 1 of 6 Crystal Red
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2,484 Posts
You might try flushing out your heater core if your tee has a restrictor and it is going to correct direction. Pull your glove box and check the blend door actuator on top of the heater A/C.
 
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