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Registered
2002 sls 1999 sts
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10 Posts
Discussion Starter #1
Hello all

I have a problem with the heater of my car. The heater will not respond to any controls except the fan. I can change the modes on the display but the mode doors will not move. I can change the
temp on the display but the blend doors do not move.

I took off the battery cables and touched them together let the car sit overnight with the battery
disconnected. I reconnected the battery started the car up and none of the HVAC controls work.

I took the control head out of the 2001 SLS parts car and installed it in the 2002 sls and it does the
same thing has no actuator movement. I tested the 2001 before removing it and it seemed to work
fine.

During all this there has been no HVAC codes.

Thanks for any help, Joe
 

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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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19,268 Posts
Hello all

I have a problem with the heater of my car. The heater will not respond to any controls except the fan. I can change the modes on the display but the mode doors will not move. I can change the
temp on the display but the blend doors do not move.

I took off the battery cables and touched them together let the car sit overnight with the battery
disconnected. I reconnected the battery started the car up and none of the HVAC controls work.

I took the control head out of the 2001 SLS parts car and installed it in the 2002 sls and it does the
same thing has no actuator movement. I tested the 2001 before removing it and it seemed to work
fine.

During all this there has been no HVAC codes.

Thanks for any help, Joe
------------------------------
can we assume you have checked all the fuses?
particularly #33 under the back seat?

and can we assume you checked for codes using the built in scanner -

with the key ON - engine OFF -
do you hear anything at all from the havc system ?

do you hear the fan from the cabin air-temp sensor -
it's behind the small grill to the left of the steering wheel -

if you turn the temp slowly up to 90* -
does the display change - but absolutely no sound?

what if you slowly change the temp to 60* -

if you push the RECIRCULATE button - can you hear anything move -

we just had a lot of rain - and 40* -
now it is in the single digits -
was the car outside in the rain -
is the car outside now -
my thought is that all the flaps on the various control doors have frozen shut -
 

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Registered
2002 sls 1999 sts
Joined
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10 Posts
Discussion Starter #4
I have checked all the fuses under the back seat and under the hood and they all check out good.
I tried to check codes with my OTC genisys and it will not access the HVAC module I checked codes with the car and it
finds one p code po480 for cooling fan circuit one. It also has two b codes b3833 and b3832 for the doors.

I pulled the cabin air temp sensor on the drivers side and the fan does not run.

I have ran the temp up to 90 and down to 60 and the display works perfectly but the blend doors do not move.

I pulled the glove box out and can watch the recirc door and it doesnt move.

The car is sitting inside the shop right now so it is plenty warm.

I think I will get an alldata subscription, then I can pin check and see if I have a actuator that is grounding out and I can also load test the powers and grounds.

Any advise is welcome, Joe
 

·
Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
·
19,268 Posts
I have checked all the fuses under the back seat and under the hood and they all check out good.
I tried to check codes with my OTC genisys and it will not access the HVAC module I checked codes with the car and it
finds one p code po480 for cooling fan circuit one. It also has two b codes b3833 and b3832 for the doors.

I pulled the cabin air temp sensor on the drivers side and the fan does not run.

I have ran the temp up to 90 and down to 60 and the display works perfectly but the blend doors do not move.

I pulled the glove box out and can watch the recirc door and it doesnt move.

The car is sitting inside the shop right now so it is plenty warm.

I think I will get an alldata subscription, then I can pin check and see if I have a actuator that is grounding out and I can also load test the powers and grounds.

Any advise is welcome, Joe
---------------------------
I just can't imagine it NOT setting any codes -
that just doesn't make sense -
 

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Registered
2002 sls 1999 sts
Joined
·
10 Posts
Discussion Starter #6
I figured out the problem with the HVAC last week and I figured I would post the solution in case anyone else runs into
this problem.
The brown 12 volt power wire that powers up all the actuators and the cabin air temp sensor fan was corroded under
the fuse box. That fan should run anytime the key is on with the heater control head hooked up or not.
Hopefully this will help someone should they run into the same problem.
 

·
Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
·
19,268 Posts
I figured out the problem with the HVAC last week and I figured I would post the solution in case anyone else runs into
this problem.
The brown 12 volt power wire that powers up all the actuators and the cabin air temp sensor fan was corroded under
the fuse box. That fan should run anytime the key is on with the heater control head hooked up or not.
Hopefully this will help someone should they run into the same problem.
---------------------
WOW - good find -
that will go into the memory bank -
 
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