Climate Control Stopped Working on Passenger Side and Rear Vents - Blows Cold Air Only

[vatodeth]

The Climate Control stopped working on the Passenger Side and 'Rear Vents' of my 2002 Oldsmobile Bravada.

INITIAL ASSESSMENT:
• I researched the problem and arrived at the conclusion that it must be the ‘Blend Door Actuator’.
• I removed the ‘Blend Door Actuator’. Yes, it was a terrible experience.
• I manually moved the ‘Blend Door’ by spinning the axle to try and get hot air blowing, but it still only blows cold air.

FURTHER TESTING:
I have further tested the issue by performing the following actions:
• I manually moved the ‘Blend Door’ by spinning the axle through it’s full range. I checked out the range-of-motion that is keyed into the actuator itself. I then rotated the blend door and verified that it is going through the full range.
• When manually rotating the ‘Blend Door Axle’ counter-clockwise (from the fully stopped position), it moves with normal resistance until the last 1/3 to 1/4. After this point, it then feels a bit loose, but it still hits the stop limit and stops the rotation.

QUESTIONS:
1. Could the issue still be the ‘Blend Door’, even though I am hitting the stop limits on both sides?
2. Is there something else that I am missing? Perhaps a system controller, causing the 'Climate Control System' to blow only cold air through the Passenger and 'Rear Vents' of the vehicle?
3. Does anyone know what ‘Fully Rotated Axle Positions’ do, in the fully rotated CW and CCW positions? I would like to know the position it should be in to allow only heat.

IMPORTANT NOTE:
I noticed the problem about a month ago. I thought it resolved itself a week later, when the weather improved. I may be wrong on this, since I don't ever sit on the Passenger Side of the vehicle. If it did resolve itself temporarily, what could the issue be?
This may be irrelevant, since I can not 100% confirm that it did start working, but I am fairly sure it did.

 

[BlazingTrails]

Welcome to the Nation! Glad you made it

It may be the temp sensor in the passenger side vent or the center vent?

 

[vatodeth]

Yes, but would that matter, if I am manually rotating the Passenger Blend Door Axle? The Passenger Blend Door Actuator is out of the equation, as I have completely removed it.

 

[BlazingTrails]

OK but the system uses the reading from the temp sensors to adjust the blend door. So if the sensor is bad it will not operate.

 

[BlazingTrails]

http://forums.trailvoy.com/showthread.php?t=80228

Have you tried the reset procedure?

 

[IllogicTC]

OK but the system uses the reading from the temp sensors to adjust the blend door. So if the sensor is bad it will not operate.

I would suspect that setting the blend door manually, and then setting the fan speed manually, would circumvent this. Dual-zone of course doesn't allow per-side selection of modes or fan speed, just temperature, and the passenger temperature actuator of course controls the rear also.

I would wonder at the possibility of getting the B-codes read. Usually takes a high-end tool to do that (does Torque Pro do Bxxxx codes?). It may have something in there.

 

[vatodeth]

My Code Reader doesn't read any codes. I don't think it is capable of reading Advanced Codes.

I have tried all of the basic stuff, like resetting, etc. At this point there is no Blend Door Actuator, so I believe that any other systems should not matter.

It seems to me that it is most likely the Blend Door. But that is odd, because I can feel it hit both end stops. That is what is confusing me.

I'd like to know if there is anything that I am missing, before disassembling the entire dash to get at the Blend Door. Any ideas are welcome.

Thanks for the feedback thus far.

 

[BlazingTrails]

Maybe the roadie will chime in soon. I am just looking over the system on all data but I don't have a lot of hands on experience with this exact system. Sorry I couldn't help more....

 

[vatodeth]

Yes, I hope he has time to answer. I am aware that he knows the HVAC system very well. He is notorious on the Inter Webs for his wisdom!

I also found this post, which is the problem that I suspect I am experiencing:
http://gmtnation.com/forums/topic/6395-dual-zone-problem/


If anyone else has any suggestions, please let me know.

 

[The_Roadie]

Notorious, eh? Sorry I was out of cell range this weekend for the most part. I think you have a mechanically broken or jammed door or blocked airflow at the heater core. As mentioned, the sensors just assist the control module to predict where to position the actuator to get the desired temperature. The sunload sensor (the little dome centered on the dashboard) also help this, by watching to see which side of the vehicle is being hit by direct sunlight. But with the actuator off, moving the door by hand bypasses the control module altogether.

1) Is the airflow lower on the passenger side, than the driver's side, as if there's debris, dust, or a mice nest covering part of the heater core?

2) Do you get good cold airflow when you ask for AC?

I don't think anyone's analyzed the exact rotation direction of the actuator to get hot/cold. I certainly haven't, and I hope I never have a problem that would require removing that much of the dashboard, although I did do about 2/3 of the work once to install a grab handle.

 

[vatodeth]

The air flow is actually stronger on the Passenger Side than the Driver Side. The heat is fine on the Driver Side. That means it can't be the heater core, unless there is heater core for each side of the vehicle.

At this point, I think it is the Blend Door. Perhaps the stop mechanism on the Blend Door is on the axle rod and not on the actual blend door. That would explain how it is hitting it's limits, but not actually diverting air properly.

I will try to determine the desired rotational position of the Blend Door by referencing the good working Blend Door on the Driver's Side. I have not looked at it yet.

If I can determine the desired rotational position, then I will manually crank the Blend Door Axle open for heat. Once I have it set, I will try to push the Blend Door to the correct position with a coat hanger. I am hoping to get the problem temporarily remedied for the remainder of the winter.

I will do this on the weekend and provide an update. If anyone has anything to add, please let me know.