2000 DeVille DHS

[TK76]

In January 2009, I inherited a very low mileage (22,000) DHS, model year 2000. Beautiful, smooth quiet car.

I do have an issue with the rear air-conditioning - it blows hot air regardless of thermostat settings front or rear.

Front AC works like a champ.

Can anyone give me a clue of what the problem might be? and what it might cost to repair?

Thanks.

[BodybyFisher]

Go to caddyinfo.com, go to how to, go to DTC codes, follow directions for your year and extract any DTC codes you might have and post them here, it will help us help you

[Cadillac Jim]

See the link in my signature block for the "How To" page to read your OBD II trouble codes.

[KHE]

Check the codes as recommended in earlier posts. I think you'll find the problem is in the actuator that controls the rear blend door position.

[BodybyFisher]

See the link in my signature block for the "How To" page to read your OBD II trouble codes.

Thanks Jim, I have to do the same, that is a great time saver

[TK76]

Check the codes as recommended in earlier posts. I think you'll find the problem is in the actuator that controls the rear blend door position.

Thanks for that lead.

Where exactly is the "actuator" that controls the rear blend door position? How do they fix that and what kind of repair bill am I looking at? BTW, the rear vents work great putting out heat any time of year.

[BodybyFisher]

CHECK THE CODES FIRST as directed in posts 2, 3 and 4, THEN we can help. I AM expecting a bad actuator, but check the codes

[Cadillac Jim]

Hopefully this is a fairly simple DIY job. If so, there will be no bill.

[TK76]

Okay men, I checked the codes on my 2000 DHS and these are the only two that showed up:

IPM B0429 CURRENT

IPM B1004 CURRENT

Does that help?

[BodybyFisher]

DTC B1004 Keep Alive Memory (KAM

DTC B0429 Temperature Control #3 Rear Circuit Range/Performance

The auxiliary air temperature actuator is an electronic stepper motor that is part of the air temperature actuator assembly. The HVAC control module supplies power and ground to the actuator. The HVAC control module controls the direction of the auxiliary air temperature actuator by changing the polarity of the control circuits. When the actuator reaches its desired position both circuits are fixed to the same value (9.5 to 12 volts). The HVAC control module determines the door position by counting pulses (voltage fluctuations) caused by the brush to commutator action generated during normal motor operation. The HVAC control module (IPM) monitors a voltage drop across an internal resistance to detect the pulses. The HVAC control module converts the pulses to counts with a range of 0 to 255 counts

Passenger/Rear Air Mix Actuator located right side of the instrument panel, on the right side of the HVAC module

[TK76]

BodybyFisher - To a non-mechanic, that sounds complicated. Is that something my local gas station mechanic can handle (he's pretty clever), or am I looking at an expensive trip to the Cadillac dealer's shop?

[BodybyFisher]

Here is the diagnostic tree, maybe this will help your mechanic. Save the 2 pages to your computer and either view it or print it

[TK76]

Here is the diagnostic tree, maybe this will help your mechanic. Save the 2 pages to your computer and either view it or print it

Thanks for the diagnostic tree images but at just 400 x 640 pixels, and with all the artifacts of severe jpeg compression, they're really not legible nor printable.

Is that material from an official GM Cadillac service manual or what?

[BodybyFisher]

Here is the diagnostic tree, maybe this will help your mechanic. Save the 2 pages to your computer and either view it or print it

Thanks for the diagnostic tree images but at just 400 x 640 pixels, and with all the artifacts of severe jpeg compression, they're really not legible nor printable.

Is that material from an official GM Cadillac service manual or what?

Its from the service manual. Send me an email address, and Ill send you the full size copy

[TK76]

'BodybyFisher': "Its from the service manual. Send me an email address, and Ill send you the full size copy"

----------------------------------------------------------------------------

Sent you an e-mail - please check your box. Thanks.

[BodybyFisher]

Send me a PM here, I didnt get the email for some reason