It seems that my heater is hissing. Once the engine warms up I get this hissing sound that sound like it is coming out from behind the heater controls, and I usually notice it the most when the heater is in the OFF position. Is this normal...what can I do to stop it?

 

Your selector is most likely worn out. If you take out the controls and look at how it is setup, you will see a little selector wheel that moves and pulls vacuum on the ducts you want open. That wheel gets loose and creates a small vacuum leak, which is the hissing you hear.

Matt

 

is it something that needs to be taken care of, or is it not worth the trouble.

 

As long as it still pulls enough vaccuum to the little flapper doors, your vents will still work right. It won't actually hurt anything on the car though. If you do decide to change it, get the controls from a similar year car and it will be about a 5 min. job.

I know for certain that the 82-89 and 90-92 wiring and vaccuum line layout is slightly different, and the faceplate size and offset is about 1mm different between the firebird and camaro. There may be other slight differences also, but I couldn't tell you what they are

Good luck

Matt

 

My 87 firebird did the samething. If you pull out your radio you can see the vacuum lines that hook into the back of the climate control. I squeezed the pieces together and it quit hissing.