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Hello,

I have a cadillac and when I got it, the ac was working just fine. Then all of a sudden, the ac blower motor would stay on and kill my battery. I now have to keep it unplugged till i need to use it. But it only blows cold air on high through the vents to defrost the windshield and it would shut off or change by the controls on the dash. I need to know what I need to replace to fix this.

Any help will be greatly appreciated.

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It won't shut off. And this is a 1995 Cadillac DeVille if that helps.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,292 Posts
Hello,

I have a cadillac and when I got it, the ac was working just fine. Then all of a sudden, the ac blower motor would stay on and kill my battery. I now have to keep it unplugged till i need to use it. But it only blows cold air on high through the vents to defrost the windshield and it would shut off or change by the controls on the dash. I need to know what I need to replace to fix this.

Any help will be greatly appreciated.

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It won't shut off. And this is a 1995 Cadillac DeVille if that helps.
======================
this is a 1995 Cadillac DeVille if that helps
that information is critical -
and should be in your "profile" -

the ac blower motor would stay on and kill my battery
start by replacing the blower motor -
I recommend the FOUR SEASONS 35121 - $91.85 - with free shipping -
http://www.amazon.com/Four-Seasons-Trumark-35121-Blower/dp/B000C2Q1TA/ref=au_as_r?_encoding=UTF8&Make=Cadillac|46&Model=DeVille|406&Year=1995|1995&ie=UTF8&n=15684181&newVehicle=1&s=automotive&vehicleId=1&vehicleType=automotive
 

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85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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773 Posts
You most likely have a bad Blower Control Module. This module takes a PWM (Pulse Width Modulation) signal from the BCM and Climate Control Programmer to regulate blower speed. It is shorted.
This usually happens when a blower gets old and starts to draw too much current. This overloads the module causing an internal short. Many people replace this module only to find that it fails within a few weeks again.
When a blower gets old it gets deposits of brush material embedded in the commutator. This causes the adjacent coils to energize to early causing the excessive current draw. The blower motor will seem just fine. It will blow air at the normal levels but it is silently overheating the blower module. The only way to properly test the blower is to do a current draw test.
Your best bet would be to replace both the blower control module and the blower motor. It will save you money in the end.
In later years, Cadillac started building the control module in the blower motor. This forced the replacement of both whenever either component had a problem.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
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19,292 Posts
You most likely have a bad Blower Control Module. This module takes a PWM (Pulse Width Modulation) signal from the BCM and Climate Control Programmer to regulate blower speed. It is shorted.
This usually happens when a blower gets old and starts to draw too much current. This overloads the module causing an internal short. Many people replace this module only to find that it fails within a few weeks again.
When a blower gets old it gets deposits of brush material embedded in the commutator. This causes the adjacent coils to energize to early causing the excessive current draw. The blower motor will seem just fine. It will blow air at the normal levels but it is silently overheating the blower module. The only way to properly test the blower is to do a current draw test.
Your best bet would be to replace both the blower control module and the blower motor. It will save you money in the end.
In later years, Cadillac started building the control module in the blower motor. This forced the replacement of both whenever either component had a problem.
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Your best bet would be to replace both the blower control module and the blower motor.
It will save you money in the end.
In later years, Cadillac started building the control module in the blower motor.
This forced the replacement of both whenever either component had a problem.


the module is built into the blower motor on this model -
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,292 Posts
So the module is in the blower motor you recommended me to get right? Not a separate part.
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correct - the module is part of the blower motor -
 

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85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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Basscat

I wasn't sure of the separate module on his year (95) so i did a part look up on Rock Auto. It does show a separate blower module for that and the next year or so. I do not have a service manual for a 95 so i could not check and we all know how accurate (sic) parts catalogs are!
I think the best way to be sure is to look on the top of the A/C Plenum box to see if the module is there.

I checked with a number of sources and they are split as to wether the module is used on the 95, Basscat probably has more accurate information then i do. Without a FSM i have no way of verifying this.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,794 Posts
:hmm: I can't swear to the '95, but I think the module is integral to the blower.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
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19,292 Posts
Basscat

I wasn't sure of the separate module on his year (95) so i did a part look up on Rock Auto. It does show a separate blower module for that and the next year or so. I do not have a service manual for a 95 so i could not check and we all know how accurate (sic) parts catalogs are!
I think the best way to be sure is to look on the top of the A/C Plenum box to see if the module is there.

I checked with a number of sources and they are split as to wether the module is used on the 95, Basscat probably has more accurate information then i do. Without a FSM i have no way of verifying this.
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once again -

WITH MORE FEELING -

the blower module is an INTEGRAL PART of the blower motor starting on the 1994 Deville -

the part I suggested IS the correct part for the OP's 1995 Deville -
 

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Registered
85 Coupe Deville 4.1 V8 & 4.3 V6 Deisel & 1970 Eldorado
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773 Posts
once again -

WITH MUCH MORE FEELING -

Basscat probably has more accurate information then i do. Without a FSM i have no way of verifying this.

I AM NOT trying to step on your toes.

This is why i tire of a lot of automotive forums. I was always try to keep a level of civility in all of my communications. Ranger challenged my findings in an appropriate manor. No one is always correct all of the time.
 
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