Was wondering how to fix my a/c controls. When I switch the controls from the cold side to hot side there is a hissing noise?
I took out the control unit and there is a grey and pink hose connected thru a rubber piece. I regreased the connection between the rubber piece and the black plastic piece that it connects to and still the noise. then i took apart the two black plastic pieces, regreased it and still the noise. also if i put my fingers on the rubber pieces and turn the controls to hot there is no leak...
- what gives? what am i missing? any ideas?

ps, the two black pieces are not broken.

 

The problem I had sounds identical to yours. I am assuming that the parts you describe lubing comprize the diverter valve at the back of the control unit. I fixed mine the same way you describe fixing yours. I took the valve apart and cleaned it real good then i greased it up and put it back together and tried it in the car. It seemed to work a bit better but not completely right...

SO, I took it back apart and after looking it over real good to see if there were anything wrong with the rubber part of the valve I got ready to put it back together. The one thing I did diffrent from you is that before putting it back together I very carefully bent the spring clip on the front that applies pressure to the two halves of the valve. After bending the spring there was more force being applied to the mating of the two surfaces and it worked fine. That was over four months ago and it is still working. I had expected that i would have had to purchase a replacement valve by now but since it is working flawlessly I will wait until I just have to...

It has worked just fine for over four months and counting...

 

Speedgraphic, I took it back apart last night and seen where the air is comeing out from... the rubber piece that sets in the middle of the diverter is used alot more then the rest of it(ie causing the leak). I'm getting the new piece tonight($8 from GM, there the only people that carry it). I'll let you know how it works out.

 

I took mine apart on a saturday afternoon after all possible sources were already closed. I started the project thinking that I probably had one or more vacuum motors that needed replacing and only discovered the diverter valve problem after I got started... I made what I had work but anticipated that I would eventually have to replace the rubber part. So far it has lasted for about four months. I guess the real test will come when hot weather returns.

It's good that the fix only costs $8 but looking at that leetle bitty part it seems a bit absurd to pay $8 for THAT!

Sounds like you've got it fixed.

Good Luck!

Speedy

 

Speedgraphic, guess what? I installed the new diverter and still the leak. Odd when the car is off(but powered on) the leak is not heard. But with it on the leak is there....
Do you think that when I converted from 700r4 to t5 and the hoses from the cruzcontrol that this is where i leak is coming from? I'm totally lost...

 

The reason that you only hear the leak with the motor running is that the vaccum comes from the motor. Without the motor running you donot have vacuum.

Are you sure you are hearing the leak at the diverter valve?

There are about four (?) vacuum motors hooked to that diverter valve. It could be that one or more of them is leaking.

I would first confirm that the leak is at the diverter valve. You can do that by listening close to the valve for a hiss. if the hiss changes as you cycle through the A/C settings at the diverter valve then that is still your problem. It could be that you need to remove the diverter valve from the head unit and disassemble it. You would then take the individual parts and clean them with something like Carborator cleaner. After the parts are clean and dry lubricate the surface that the rubber air routing disk contacts with white lithium grease. Do this lightly. The grease helps seal the vacuum connection. (Do you remember the old bicycle tire pumps. The rubber gasket around the plunger had to have oil to help it maintain compression - this is the same thing...) If you put too much grease in there you will clog the passages in the are routing disk. If you don't have enough you won't have a seal.

Like I said before - listen at the head unit to be certain that that is where the leak is - THEN do the above...

Good Luck!
Speedy

 

How is your vaccum routing problem coming? Have you gotten it fixed yet?