Cadillac Seville / Cadillac Eldorado Forum Discussion, Mode Door Issues- No Error Codes in Past Cadillac Vehicle Discussion; 2002 STS A/C worked great except lately the mode door switches from dash vents to defrost/floor vents. It did it ...
2002 STS A/C worked great except lately the mode door switches from dash vents to defrost/floor vents. It did it once several months ago and then worked normal until a couple of weeks ago and now its doing it almost all the time. First morning start, it takes 3-4 minutes before it switches; later starts during the day, it switches after about a minute. You can hear the door move and it appears to do so without hesitation, etc. Its like something is telling the mode door motor to change. I pulled the codes and NO CODES current or in history.
If I wasn't in Tucson (temp will probably hit 104 degrees today), I could live with it, but living here I need to have the air coming out of the A/C vents.
2002 STS A/C worked great except lately the mode door switches from dash vents to defrost/floor vents.
....You can hear the door move and it appears to do so without hesitation, etc. Its like something is telling the mode door motor to change. I pulled the codes and NO CODES current or in history.
IF (and it's a big IF) you are operating the HVAC in AUTO mode, what you are describing "might be" normal operation. In AUTO mode the only driver input is temperature selection; the system decides everything else including where the air flow is directed and blower speed.
On the other hand, if you are manually selecting where the air flow is directed you could be experiencing a door actuator showing early signs of failure. You say "You can hear the door move...."; that surprises me because in 13 years of Seville ownership and 4 overlapping years of Deville ownership, I swear I did not hear any HVAC door movement when changing modes (or at anytime).
The potential good news is many if not all the door actuators are electrically the same as in interchangeable. Which leaves the question about mechanical output compatibility. That might make diagnosis a little easier.
Thanks for your replies. I can't hear the actual moving of the opening and closing of the mode door but I do hear a slight "thunk" at the end of it's position change as it seats into it's final position which I would assume is normal.
The temperature is set in the low 60's most of the time; the fan speed is set usually at 3 and then lowered to 1 when the car has cooled off inside.
If the actuator motor fails, wouldn't it just stop in whatever position it is? This seem like something is "telling" the motor to move.
Assuming that the actuator motor is bad, where is it located? In the console? An illustration submitted by Ranger in reply to an earlier inquiry indicated the components for a 2004 Seville but didn't indicate the location; is it the same for my 2002 STS? Please clarify.
If replacing the actuator motor seems like a probable solution, where's the best place to purchase. I bought the front hub/bearings from Amazon and that worked out fine.
What's involved in permanently positioning the mode door so that the air (hot or cold) always comes out the dash vents? Unless this would be relatively simple and not involve tearing into the bowels of the system, I would probably rather buy an actuator motor to fix it right.
....Assuming that the actuator motor is bad, where is it located? In the console? An illustration submitted by Ranger in reply to an earlier inquiry indicated the components for a 2004 Seville but didn't indicate the location; is it the same for my 2002 STS? Please clarify.
The location is not clear but you can bet the mode actuator is somewhere on the HVAC plumbing buried under the instrument panel and behind the various front panel controls. Somewhere.
The electrical schematic diagrams at my fingertips for the HVAC system clearly refer to 4 separate door actuators in the front seat HVAC control circuits. None of the sources at my disposal have a location diagram for the "mode" door actuator.
Referring to my 1998 Seville printed Service Manual there is a clue in the section that deals with Mode Actuator Replacement. The first step says "Remove the IP carrier". Flipping to the pages that deal with Replacing the IP carrier, there are 40 detailed steps detailing Removal Procedure. It might not be necessary to completely remove the IP carrier to gain access to the actuator(s) you are interested in, but the process is hardly a Saturday morning job. Maybe someone who has been there done that can detail a shortcut method.
Back to the Mode Actuator Replacement. The second step in my 1998 Service Manual says "Remove the driver air mix actuator retaining screws." Apparently the driver air actuator blocks access to the mode actuator mounting screws.
In your shoes, I would wait for the HVAC onboard diagnostic system to accumulate sufficient position errors for long enough to set a code. I would want that code for confirmation of the failed component; no guesses, no speculation.
Try this thread it has everything you need to know. Except that I ordered the actuator it recommended and the plug was different so it would not work. Gmpartsdirect.com says it has there right one I need but I am waiting on and email from them to confirm the part number. Oh an the mode door actuator is located above the floor vent on the drivers side. It is the hardest one to get to but it can be done. To get the air to stsy blowing through the vents some have just unplugged the actuator when it is blowing in the vents.
Thanks to everyone who responded. I spoke with my mechanic and am meeting with him Monday A.M. We'll decide whether to get the part and replace or unplug the motor when the air is directed through the dash vents. In Tucson, I probably don't need air to come through the floor vents ever, but if it's going to be torn apart anyway, it might be best to go ahead and replace the part. Any feelings one way or the other?