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2003 Auto Climate Control, driver's side hot, passenger cool on Auto @ 60*

dano

Full Member
Joined
Dec 3, 2004
Messages
48
Location
Central Ohio
Hello all, I have a 2003 Av with the automatic climate control.  With both driver's and passenger sides set to 60 degrees in auto mode, I initially get cold air on both sides but the driver's side then goes to hot while passenger stays cold.  I replaced the climate control panel thinking it was the obvious culprit but it does the same thing with the new control.  Problem is intermittent, outside temp has been 65 and today was 78 and it did it both time.  The other day it was 75-80 degrees and it behaved all day.  Also, I replaced the battery a few days before this problem came about.  I have read something somewhere about calibrating servos for vents but that doesn't seem to be the issue, it starts out blowing cold then goes hot and stays hot after 20-30 seconds.  Thanks for the input.
 
Henry3, can you elaborate?  Is the blend door held in the cool position by a motor when commanded and does it naturally go to the heat position if the motor fails? 
 
I just now found many posts on actuator door issues.  I searched around a lot before posting but apparently I didn't know what to call my problem.  I have read the HVAC 101 post also for the auto climate system.  My vents are assigning correctly, defrost, dash and floor.  My issue is just the driver's side gets hot when it should be cold.  Looks like there are at least 3 actuators?  I guess I will tear apart the dash tomorrow and see if I can find the door that blends hot or cold to the left side.  I'm guessing its on the left side?
 
I am not sure if it has a default position to fail in. It seems to fail inbetween. This directs hot air to part of the system instead of moving fully one direction or the other. Mine did just as yours. AC on the driver's side blew hot air. Passenger side cold. Pretty common failure. Parts guys will know exactly what you are looking for. Check Rockauto.com for pictures of the module.
It is pretty easy to get to. Two screws hold it to the bottom of the HVAC assembly just over the transmission tunnel. Unplug it and replace. If you have to wait for parts, you can remove the defective unit and turn the shaft manually.
Mine had symptoms of failure including a flopping noise at idle under lower voltage conditions. That has since gone away.

The Blend door is used to dry the air during defrost. Seems a little crazy to use the AC when you are trying to clear the windshield, but that is indeed how it works.
 
Thanks for the info. I checked rock auto and they have a whole bunch of actuators listed.  I will remove mine and check by moving the door by hand if possible.  Sometimes I get a weird noise down low sometimes that sounds like a fan motor running slow and hitting something, or a gurgle.  But it does it with engine off too.  So maybe this is the culprit.  I will update when I solve it. 
 
dano said:
Sometimes I get a weird noise down low sometimes that sounds like a fan motor running slow and hitting something, or a gurgle...
A good description of what I had been hearing too. Hope this solves your problem :)
 
Today I removed what I believe is called the temperature blend door actuator, thanks to advice from several different users.  With the actuator removed, I was able to twist the door into different positions and replicate my problem.  In addition, it is almost nearly impossible to move the blend door by hand when the blower is at full speed; the airflow over the door is too much and causes the door to blow shut, which explains why it fails in this mode.  The actuator becomes weak over time and cannot hold the temperature blend door against the airflow.  Here are pics of the actuator location and what it looks like:



 
Thanks for the pictures! That will help the next guy for sure.

You could probably plug in the wiring and see if it moves properly, but I suspect that it does not. Now to see if a new one solves the problem?
 
Actually I think found the problem with the current actuator motor.  My earlier assumption that the airflow was blowing this motor to the wrong position is probably wrong. The gear reduction inside this thing is more than strong enough to hold against some pretty good force.  There's no way the blower door was forcing this motor to rotate.  It now seems likely that the motor was driving itself to that position in error.  Member Trey alerted me to a possible cause, and it seems he was correct.  The position cam on the actuator has two fingers on it that contact an area on the circuit board inside the actuator.  I'm guessing this is a type of potentiometer or crude encoder, either way, I'm positive that it is what the actuator uses for position feedback.  The fingers on the position cam had grease all over them, as did the areas of the circuit board that they contact.  I cleaned up the fingers and the circuit board and snapped the cover back on and put it back in and POW!, it is working as it should. I ordered an AC Delco replacement on Amazon for $35, I will throw it in the glove box for now just in case. 
 
Here's what I found:  first pic shows the actuator.  Pop off the upper cover by releasing the 5 tabs:




Then remove the TOP white gear.  Note position of the black cam, this is the part that interfaces with your blend door.  Now remove the black cam.



Finally, clean the little copper fingers on the bottom of the black cam, and clean the circuit board in the semi circle shaped area the copper fingers ride on ( see below where screwdriver is resting).  Mine had a blob of grease on the fingers and on the circuit board.  If you don't see a bunch of grease this might not work for you.  I checked the grease with a multi meter and it conducts pretty well.  Certainly more than enough to mess up your position feedback. 



Snap it back together and install it and see what happens.
 
There are a variety of things that can go wrong with these blend door motor assemblies.

Here's where someone posted on a corvette forum where the cause was cracked plastic gears and how he fixed it.

http://www.corvetteforum.com/forums/c5-tech/2768053-how-to-fix-repair-hvac-climate-actuators.html

I've also read where someone successfully got one working again by replacing the actual motor.
 
HenryJ said:
A good description of what I had been hearing too. Hope this solves your problem :)





No comment back about the noise. You described what sounds to me like the expansion valve equalization when turn an a/c system off. Maybe not though?
 
Our AC uses an orifice tube :) Mine sounded like the door sort of flopping or thumping lightly.
 
orifice tube/expansion valve=same. The noise you were hearing is likely from the actuator since the noise I suggested is heard after engine shut off.
 
tag... hopefully this is my issue but my sound is after turning the hvac on there is a loud thump or thud  :E:
 
My specific noise was similar to a heater core gurgle like when you're low on coolant, but in this case was not rpm specific.  Actually, I even turned off my engine abut left the key on and still had the noise.  When I had the actuator motor removed, I could move the door back and forth a little each direction and duplicate the noise.  I'm thinking the door was modulating back and forth a small amount and causing the noise.  Even turning off the HVAC did not make the noise go away.  It was in the general vicinity of the blend door and I haven't heard it since, so I'm thinking this was it----however I bought a new Civic SI and haven't been driving this much.
 
UPDATE:  My gurgling noise was definitely this actuator.  I have not heard it since.  My noise was similar to one I had previously on another vehicle that was low on coolant and the air and coolant would make a gurgling or sometimes whooshing sound as it went through the heater core.  And sometimes it sounded like water running down a drain but it was always kind of faint.  In this instance on my Avvy, it would make noise with key on and engine off.  After replacing the actuator the noise is gone. That should help most of you narrow it down. 
 
any 2003 chevy with split system is prone to this problem . i found the best way to fix it is replace the blend door motor actuator have had to to do it twice in my wifes 2003 tahoe
 
(y) Oh man I just joined and thanks for your info and pic's. I'm a new owner of a Avalanche you guys would dream of finding. The A/C is blowing hot on pass and cold on driver side. I'm going to pull it apart tomorrow now I've seen your post. Thanks for the info...see yall  :wave: 
 
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