Of course, since I moved things during a different repair my HVAC selector disc now hisses in any position other than "OFF". If I apply slight pressure side to side the hiss will stop. All settings operate properly but I have a varying idle due to the vacuum leak. I'm thinking of applying white lithium grease to the disc face and around the circumference. Anyone know of a reason NOT to try this?

I had this problem with my 92 GTA last year. I remember trying all kinds of things to get that hissing noise to go away. What had happened was the clip that holds the whole thing together had cracked and was causing it to lose vacuum. I never tried the lithium grease, however. Still, I figured it wasn't worth it considering a new part only cost me $13 or so (if I remember). You can get the whole thing, ACDelco part# 1571350. Also if I remember right the dealer wanted to charge me $40 for that! Look it up to make sure its the part you need, you should have no trouble finding an image of it. It's incredibly easy to install. I kicked myself for going through the trouble of trying to fix that thing.

having idle problems? seen as vac leak,the control switch (electrical was @18 at GM

I'm not sure what that big thing above is, but I know the mechanical control selector in my 83 leaks anything above OFF too. Thank goodness I'm not the only one. What a crappy design! I'll have to see if the new one is still available

Thanks!

EDIT: I can't come up with 1571350 as being an active GM #. Anybody?

The grease worked until I cycled the selector a few times. I guess the grease just moved too much. If I could get the HVAC control out without ripping out the whole pod, I'd be ecstatic. I can't see why the vacuum lines and cable could not have been 4-6 inches longer.

Mine hisses too. I was going to try to jury rig something, but it was too much of a pain to take out.

Where can you buy that clip? Dealer?

man i tried buying that part and the autoparts stores sent me to the dealer, and the dealer said it was discontinued!! so which places sell ac delco?

If the dealer can't get it we may be hosed. Crap!!

There has to be another model GM that has a control that'll fit.

icarus I was thinking that. In the same era other cars, GM must have reused the disc assembly in another HVAC control. The problem is, those are probably worn out and also unavailable new. I hope someone comes up with an answer!! I could probably take mine apart and cut a gasket to fit, and bond it to one of the discs, and grease it and see what happens.

I'm hitting the JY this AM. I'll let you know. Maybe I'll wind up converting to
4th gen. Then I could collect a number of controls.

No luck yet. OAll the 3rd gens were stripped. I took a chance and grabbed one out of an early 90's Sunfire but it didn't match up when I pulled the original yesterday morning.

If you take the disk controller apart, you'll find a black rubber disk inside. It's held in place by a pin thats part of the rubber disk. When the rubber starts getting old, the pin starts to break off. That allows the rubber disk to spin around inside the controller and cause weird hissing noises, wrong vents, etc. Glue the rubber disk down to keep it from moving and use a bit of silicon gel to lube it.

I'll try this on the spare I got out of a Sunbird. I can't believe they reconfigured the exact same control functions on the exact same control for different models. i found maybe four configurations on 5 or 6 different HVAC controls from near same year models.

I found no rubber inside the disc. All it is made of is two discs with grooves to direct the vacuum signal when one side of the disc moves.
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Do you have any pictures? what year and model do you have?

84 Firebird, Is the disc that moves (with the groves) is held in place with a pin?

There is rubber in there, I pulled it apart and let it soak in Aero Kroil for about 2 hours, and I haven't had any trouble since

That is what I needed to know. I will soak mine in brake fluid, which will swell rubber as well. Thanks

Glad I could help

I know it's not the cheapest way, but I bought a whole new heater control unit. That way I know I'm getting new stuff, I don't remember what the list (customer) price was, but I got it for under $100.

One day I'll get an engine hooked up to it to see if I got rid of that hissing. BTW, mine had got to the point where all it would do is defrost. Nothing else worked, the leak was that bad.

Did you soak just tyhe disc?

Yes, I pulled it apart, but you have to be very careful when you do this, the plastic is very fragile after this many years, and the 2 plastic prongs that hold the valve together will break extremely easily

v6 canvas, my heater is to the point where it only defrosts too

I am gonna admit, im a total noob especially with the heating.

I have a 92 camaro rs and its to the point where it only will come out of the defrost, it also hisses really loud even a little when it's turned off. I heard a bunch of people saying you could just soak it in brake fluid and it would fix itself? i am just wondering if someone could explain what i'm going to need to do to fix this w/possibly pictures. is everything you need to fix/replace right behind the controls? thanx

Sorry for the late reply, but that part number came from the AC Delco cataloge, Here is the actual part number: 15-71350 . I forgot the dash. Here is what the part looks like, this is that part that was hissing for me. I also had to buy the part from an online parts store, although it was so long ago I don't really remember what site it was (it allowed me to search parts by ac delco part#).

Advance Auto will let you search by the AC Delco part number and it will return this part. NAPA and AutoZone do not return this part number. Or you can try the AC Delco site and look for a shop that will sell you the part. In the area of Kansas City that I live there are several Goodyear Repair Shops that sell the AC Delco parts.

Dave

I found the above part at the following link:

http://www.acdelco.com/index.jsp

JamesC

I ended up braking that part somehow when I was putting it in. I then was able to buy just that part and installed it w/o braking it. I'll have to see if it's fixed whenever I get the car running again.

At my nearest dealership 15-71350 was discontinued and for a Buick. They looked it up for my 92RS and found part no. 1603-2395. Cost is $24.44. It'll be there in 4 days. Cold weather's coming.