Ramified5.9

Yes I searched and read two hours worth of posts but none relating to what my issue is.

NOTE: This is referencing my 2005 QC 4x4 truck, NOT the one in my signature...

OK, my blend door does not appear broken, there is no stipped sound, in fact it works great when it wants to. This is the issue. The control **** when moved to cold does not quite get the air switched from the hot side. It starts to and the air will stay luke warm. If I play with the switch, I can get the door to stay on the coldest setting. Now if you look at the blend air **** wrong and barely touch it, it wil pulsate between hot and cold a few times then it will go fully hot. I have also had a few times before when it would stay on hot momentarily then go fully to the cold side, but primarily, it wants to stay on hot.

It's easy to get it to go to hot, it's getting it back to cold thats the issue now. There is really no in between either. It just wants to pulsate until it finds where it wants to stop regardless of where the switch is.

So, I pulled the switches out of the dash and disassemble them only to find they are microproceser controlled.

So, what next? Does this sound like a switch problem or actuator problem OR???

Thanks for your help and insite!

Jeff in TD

My guess would be that the door or coupler is stripped.

The thing learns its range of motion by running the door to one stop, where the motor stalls, to the other stop, where the motor stalls.

If something travels farther than it should, it apparently confuses the controller.

carri56

visit this website
www.heatertreater.net
Hope this helps

BigDave12768

Well your somewhat in luck. The accuator that controls the heat cold blend door is easy access just by removing lower dash. It has a bar coming off it that goes down towards the passanger foot area. If you remove the bezel you can see it. But the lower dash has to be removed to replace it.

Ramified5.9

Thanks for the responses. Here's an update. I took a look at the actuator and arm assembly, and it is all moving as it should. You can hear the cold/hot blend doors seals tightly squeezing at each end when the moving the **** from hot to cold. There is no thunk, stipped sounds or crunching. I think the issue is my HVAC controller in the dash. It is controlled with microprocessors (open one up and it will look like a computer chip board). I'll check a price on one from the dealer and if it's too much, snag one out of a junk yard for diagnostic purposes.

Another idea, does anybody possibly have details on checking resistance on possibly the HVAC plug socket on the back of the controller? This may diagnose the controller as well if I knew what the ohms resistance should be at each click of the ****.

One other off the wall issue that may be related, and maybe someone could elighten me on this possibility. I need to replace my clutch fan assembly due to it's shot and sounds like a bucket of rocks when the motor is running, (yes I also have a fan clutch code). Do you think that the fan clutch being bad could be shorted and possibly affecting the HVAC operation? Kinda along the same lines of the issue with the shorted 5 v signal wire that is found to rub through on the A/C compressor housing causing funky codes and drivability problems on our trucks? Fuse to the fan clutch is not blown, so I doub't this has any bearing on my HVAC issue, but thought I would ask anyway.

Thanks!

Jeff in TD

So are you seeing the blend door rod pulse around when you try to put it on one setting or another, or does it move from one end of its range to the other when you move it from hot to cold?

In any case, I think I would correct the fan clutch problem first, and then see how it acts. Not having air moving through the condenser would cause no cooling, and perhaps the fan clutch error code has the climate control unit in some sort of limp mode?

I still suspect you have one or more broken parts on the blend door. They don't always make abnormal noise when they have failed. Also as I understand it, the module learns the range of motion of the blend doors from where the motor stalls when the coupler hits the stop molded onto the housing, so if something binds up, or something is stripped or the stop piece has broken off it can act really weird.

BigDave12768

just so you know. There are about 6 different revisions of the A/c climate controller and its not plug and play. You have to have a scan tool and change things to make it work.

I am having problems wih an 04.5 right now. My blend doors move also. And things work when they want to. I have a new controller. I have to check all data to see if I can get it to work with a snap on scan tool

Ramified5.9

Moves on its own from one range to another from hot to then cold about 3 times then it stops in either the hot or cold position wherever you have the dial. There seems to be no fine tuning in between blend of the air. It's either hot or its cold, not warm thus blending the two in between.

Sometimes though it will stop in a warm blend setting if you go to one extreme to another with the ****. But to overcome this what I have been doing is pulling the **** out part way (as if you were going to pull it off) and then turn the **** about 1/4 to 1/2 inch more past the stop built into the dial **** backing. This seems to make it go to the full hot or cold position depending on the respective dial position. But it takes a few turns of the **** back and forth to get it to the full hot or cold position.

Big Dave, thanks and please post if your fix works with your new controller and the steps you have to take to make it work.

Jeff in TD

For now (summer) you could install a manual coolant valve on one of the heater hoses, until you get it figured out.

Ramified5.9

Ha Ha, this is Colorado. It's winter in the morning and then Summer in the afternoon!

I can get it to work either hot or cold, it's the issue of not being able to get it to that "just right" warm temp in the middle.

BigDave12768

I am going to tackle it on monday at my friends garage. He has the All Data set up and a Snap on can tool