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2004 Cadillac DeVille DHS
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280 Posts
Discussion Starter #1
Guys,

Last May, my wife and I purchased a 2004 Cadillac DeVille DHS. Since the weather was warm we had the opportunity to check out the air conditioning system, but not the heating system. I read through the owner's manual to check out all of the controls and the manual seemed to indicate that when in AUTO mode, the user doesn't need to do anything to get heat...the system takes care of the whole operation. Last night I took the car out when the temperature was 23 degrees, so obviously heat was needed. I set the inside temperature to 74 degrees and left the system alone in AUTO Mode to see what would happen. What happened, basically, was nothing. After about 15 minutes, the fan never turned on, so the car never warmed up. Finally, I turned on the fan manually and then I got heat. The manual seems to indicate that the system should turn on the fan automatically and control the fan speed automatically.Either the system is broken and I need to get it fixed, or I don't know what I'm doing and am too dense to understand the manual. (Either is possible!).

Can someone who has a working heating system tell me how your system operates so I can see whether or not I need to take advantage of that expensive warranty that I bought? Thanks in advance...!!!

Bob
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,441 Posts
Does the 2004 still have the built-in trouble code reader/scanner, and if it does, did you use it to find any DTC's for the HVAC system ? Most of its functions are monitored, and there should be trouble codes. You might also check the aspirator fan tunnel and see if the sensor is clogged with dust.

The sticky post ^^^ "How to pull codes" and Google "cadillac forums deville cabin air temperature sensor" - not the outside/ambient sensor, the internal cabin air temp sensor behind the dash grille just left of the steering wheel.
 

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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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19,268 Posts
your understanding of the system is correct -

If in FULL AUTO mode - all you need to do is select the temperature you want -

when the engine is warm enough to produce heat inside the car - the fan will start -
as the engine heats up more - the fan will increase speed - to heat the cabin faster -

as the desired temp is getting close - the fan speed will lower -

the system will also choose the "best" vents to use -

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

when ever anything doesn't work properly on your car -
the very first thing you should do is check for Diagnostic Trouble Codes -

if you don't know how - go here and read the ENTIRE post -

http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/138257-how-pull-codes-dtcs.html

if you have any codes - post them here -
ALONG WITH THEIR DEFINITIONS
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,781 Posts
So the blower will not work in AUTO mode, but does work in manual? :hmm:
 

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2004 Cadillac DeVille DHS
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280 Posts
Discussion Starter #5
So the blower will not work in AUTO mode, but does work in manual? :hmm:
That's correct. If I press the FAN control the fan will turn on, and the more times I press it, the faster the fan runs till it hits maximum speed.

When I was driving the car last night, the engine was completely up to operating temperature, but still no fan.

Based upon a couple of the posts above that confirmed that my understanding of the system operation is correct, I will need to look into this a little further. For instance, the manual states that if I press the FAN button, the system goes out of AUTO mode and enters MANUAL mode. However, I seem to remember that the AUTO indicator was still on in the display after I pressed the FAN button. Before I lead you guys down the garden path any further, I'll make sure that I get all of my facts straight, plus I'll read the section on pulling codes to see if I'm able to do it.

Thanks, again, for the ideas.

Bob
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
There is AUTO FAN, and AUTO MODE. Pressing Auto sets both to auto. Manually selecting a fan speed will not effect AUTO MODE, and it will remain illuminated.

Is your ambient temp readout accurate?
 

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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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19,268 Posts
There is AUTO FAN, and AUTO MODE. Pressing Auto sets both to auto. Manually selecting a fan speed will not effect AUTO MODE, and it will remain illuminated.

Is your ambient temp readout accurate?
------------------
There is AUTO FAN, and AUTO MODE.
Pressing Auto sets both to auto.
Manually selecting a fan speed will not effect AUTO MODE,
and it will remain illuminated.

---------------------------------:yeah:--------------

and with the fan in the manual mode -
the MEMORY SYSTEM will keep the fan in the last position it was in -

so - if you manually selected a real slow speed -
the next time you started the car -
the fan would still be in the manual mode - with a real slow speed -

some of this climate control memory stuff - and radio memory stuff for that matter
are affected by the VEHICLE PERSONALIZATION settings -

the CLIMATE CONTROL PERSONALIZATION settings
are explained on page 3-40 in the Owners Manual -

and - just for kicks - RADIO PERSONALIZATION is on page 3-104 -

on a side note - if you would like a copy of the Owners Manual for your computer -
follow this link for a free downloadable copy -
http://www.manualowl.com/am/Cadillac/2004-DeVille/Manual/220


http://www.manualowl.com/am/Cadillac/2004-DeVille/Manual/220plus I'll read the section on pulling codes to see if I'm able to do it.

http://www.manualowl.com/am/Cadillac/2004-DeVille/Manual/220it's really easy - I had my 85 year old Mother do it over the phone -
when the CHECK ENGINE light came on -
then I had her clear the code -
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,781 Posts
Very strange. Based on what you (DevilleNut) are saying, everything is operating as it is supposed to except the Auto fan mode. I cannot think of anything other than the Blower Control Module (generally pretty reliable).
 

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2004 Deville DTS (traded), 2018 CTS-V
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78 Posts
Only thing I can think of, besides the module, is a sensor misreading. Is the temperature gauge on the dash working correctly? I know on my car, in auto mode, the fan won't ever start until the car is halfway warmed up.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,781 Posts
If I remember correctly, the blower comes on low when the ECT is about 90 Degrees. That's just about the time it comes off the peg.
 

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1991 Cadillac Brougham D'Elegance 5.7 Litre, 1994 DeVille
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6,796 Posts
Very strange. Based on what you (DevilleNut) are saying, everything is operating as it is supposed to except the Auto fan mode. I cannot think of anything other than the Blower Control Module (generally pretty reliable).
I would have thought that if the fan will work in manual that the blower control module is working properly and it's the climate control system not telling it what to do is the problem.

It seems like either the system doesn't know that it's cold in the car and it needs heat, or that it doesn't know when the engine is starting to warm up to start running the fan.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
Well he still hasn't pulled codes, so a faulty cabin air temp sensor is still a possibility. And he also hasn't been back to answer my question about the ambient temp reading.

The only thing about those two scenarios, is that he hasn't complained that the air coming out of the vents, when the fan is turned on manually, does not correspond to the set temp.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,781 Posts
I would have thought that if the fan will work in manual that the blower control module is working properly and it's the climate control system not telling it what to do is the problem.
That was my first thought (Programmer), but in looking for it, I could not find a programmer. All I found was the Blower Control Module. I suspect that may be what used to be called the programmer aka ACM (Air Conditioning Module).
 

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2004 Deville DTS (traded), 2018 CTS-V
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78 Posts
This is the Description/Operation of Auto Mode, not sure if it helps be might give someone an idea

Automatic Operation
In automatic operation, the HVAC control module (IPM) will maintain the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, mode actuator and recirculation.

To place the HVAC system in automatic mode, the following is required:


The blower motor switch must be in the AUTO position.
The air temperature switch must be in any other position other than 60 or 90 degrees .
The mode switch must be in the AUTO position.
Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators will automatically adjust to maintain the temperature selected (except in the extreme temperature positions. The HVAC control module (IPM) performs the following functions to maintain the desired air temperature:


Monitors the following sensors:
Inside air temperature sensor
Ambient air temperature sensor
Upper duct sensors
Lower duct sensors
Sunload sensor
Regulate blower motor speed
Position the air temperature actuator
Position the mode actuator
Position the recirculation actuator
Request A/C operation
When the warmest position is selected in automatic operation the blower speed will increase gradually until the vehicle reaches normal operating temperature. When normal operating temperature is reached the blower will stay on high speed and the air temperature actuators will stay in the full heat position. When the coldest position is selected in automatic operation the blower will stay on high and the air temperature actuators will stay in the full cold position.

In cold temperatures, the automatic HVAC system will provide heat in the most efficient manner. The vehicle operator can select an extreme temperature setting but the system will not warm the vehicle any faster. In warm temperatures, the automatic HVAC system will also provide air conditioning in the most efficient manner. Selecting an extreme cool temperature will not cool the vehicle any faster.
 

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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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19,268 Posts
below is right from the Owners Manual -

Climate Controls Personalization

If your vehicle is equipped with this feature, you
can store and recall climate control settings for the
temperature, the fan speed and the direction of
the airflow.
Memory buttons 1 and 2 are located on the driver’s door
panel and correspond to the numbers 1 or 2 found on
the back of each remote keyless entry transmitter.
To recall the climate control settings last stored on your
transmitter, press the unlock button on your remote
keyless entry transmitter and put the ignition in
ACCESSORY or ON. The settings will be recalled.
To change the stored settings, do the following:
1. Select the desired temperature, fan speed and
airflow mode. If desired, a separate temperature
setting may also be selected for the front seat
passenger. For information on how to do this, see
Dual Climate Control System on page 3-31.
2. Locate memory buttons 1 and 2 on the driver’s door
panel.
3. Press the memory button on the door panel that
corresponds to the number on the back of the
transmitter you are programming, until you hear two
beeps. The beeps confirm that your selection has
been saved and can now be recalled. For more
information on the memory feature, see Memory
Seat, Mirrors and Steering Wheel on page 2-56.
Follow these steps each time you want to change the
stored settings.

so - my suggestion to the OP -

follow the instructions on To change the stored settings -
reset the fan to the AUTO position - and see what happens -
 

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2004 Cadillac DeVille DHS
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280 Posts
Guys,

Sorry that it's taken some time to get back here, but based upon some of the comments above, I wanted to drive the car again to check some things. I had a medical appointment this afternoon, so I started the car and then looked at the Climate Control Indicator panel. It showed a temperature of 74 degrees, and the word AUTO was lit. I started to drive and when the engine was about half way warmed up, there was still no fan. Then I pressed the AUTO button on the Climate Control Center and immediately the four-blade fan symbol lit up with another word AUTO next to it. (Now there were two AUTO symbols lit.) The fan started running relatively slowly, but then began to speed up as the engine got warmer, and then slowed down again as the car got warmer inside. This seems very much like what some of you described, above. When I got to my appointment, I pressed and held the "1" button on the drivers door to save the settings that I had, but the system did not beep two times like the manual stated that it should. The manual doesn't state whether the user should press the SET button first, and whether or not the ignition should be ON or OFF. I'll have to try a couple of different ways and see what happens.

After my appointment, I unlocked the car with the remote, and then started it up. The system was still in the state where I had left it. When I began driving, the fan did not turn on as it had before with everything in AUTO mode. I pressed the AUTO button again as I had the first time, but still no fan. In order to get the fan to run, I had to press the temperature knob to turn off the system, and then press it again to turn it on. Then the fan came on properly.

I believe that the bottom line is that the system is probably working alright...I just don't understand how to use it properly. I've probably misinterpreted some of the things that the manual was saying, and perhaps it could have been clearer in a couple of places. I had never tried pressing the AUTO button before since the display showed AUTO when the car was started.

I'm sure that all of this looks pretty dumb to some of you, but you've got to remember that before buying the '04 DeVille, the newest car that we owned was a 1973 Buick Century and the only electronic device in it was the radio.

I really appreciate all of your suggestions on this...and now I know how to pull codes if I need to in the future.

Bob
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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For the memory feature, you must first press Set, then 1 or 2.

Something still doesn't sound right. You should never have to turn the system off and on for the fan to run, regardless of temp.
 

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2004 Cadillac DeVille DHS
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280 Posts
While I was in the medical office, the car was in the parking lot and the sun was hitting it at about a 45 degree angle. It's cold up here in New Your State, but it could be that because of the warmth from the sun, the cabin temperature sensor still thought that the temperature was within the set range, even though the car felt cool inside. Maybe the fan didn't run for that reason. Perhaps turning it off and then back on "kicked" the system to turn the fan on. I'll see what happens when I go out to the garage tomorrow when the car really is 25 degrees inside and then I can see if the fan will start up without having to toggle the Temperature knob.

When I store settings in my car by pressing the SET and number buttons, the system beeps ONCE rather than twice as it states on page 3-40 of the manual. That was why I was questioning whether the settings had taken. My car requires the SET button to be pressed before pressing the number buttons, as you stated above.

Bob
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Even if the cabin temp was close, or even AT the set temp, the fan would still run on low. The fan should never be OFF with the system ON. Any time you manually adjust the fan, it should come on, no excuses, no need for a "kick".

Even with odd symptoms, I wonder if this could be a blower motor problem. Just for the hell of it, next time the fan doesn't turn on (but the system IS on), give the passengers side of the dash a god whack with your palm, or slam the front, passengers door a bit.
 

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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
Bob - go to page 2-56 in the Owners Manual -
Vehicle Personalization

copied from the OM -

1. Adjust the driver’s seat, including the seatback
recliner and lumbar, both outside mirrors and
the steering wheel to a comfortable position.
2. Press and hold the SET button. Release the SET
button when you hear a single beep.
3. Within five seconds, press and hold button 1. After
a brief delay, a single beep will sound through the
driver’s side front speaker to let you know that
the position has been stored.
--------------------------
as I said earlier -
the Memory System - Vehicle Personalization - and Feature Programming are tied together -

you need to understand all three sections - and set them all up the way YOU want them -

check out the section - DIC Vehicle Personalization - starting on page 3-70

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

I see one problem that is causing you some grief -
the instructions for setting the memory up on page 3-40 is WRONG -

the method I posted above is the correct method -
 
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