Guys,

I've narrowed down my problem to a AC/Heater vacuum leak in my 91 Camaro. I have the typical "hissing" sound inside the car as soon as i move the controls out of the off position. The problem that i am having is that this leak doesn't allow the heater control valve to open up and heat up the car when it's cold. All other problems have been fixed ( i.e. no coolant leaks, new heater core, new heater control valve, and correct amount of antifreeze in system).

Have any of you here fixed this problem before? I would assume that i could go out and buy regular vacuum hose to replace all of the lines, but some look manufactured rather than just regular hoses. Any advice would be greatly appreciated.

Thanks,
Scott

 

If you remove the HVAC control panel you will see a small disc with a bunch of prefabbed vacuum hoses on it. This is the leak. It is made of rubber and dries out after time.

You have 2 options- replace it for about $20 from the dealership or fix it.

To fix it- remove it from the panel- it is held in by a few 7mm screws. There is a small spring clip(s) holding it together. CAREFULLY remove it- the plastic is fragile and can break as well as the clips. Inside is a rubber disc- remove it and put it in brake fluid for about an hour (or longer depending on how long you can be without it). The brake fluid will cause it to swell slightly and seal again.

It is only a temprary repair- it will last for about a year. You are better off replacing it with a new one.

 

After replacing the rotary valve mentioned above, I figured out that the problem with mine was the harness that plugged into the rotary valve. I tried to coat the harness end with silicone dielectric grease, but it still leaked. Finally, I got some small-diameter silicone tubing that fit over the nipples on the rotary valve and snugged them into the harness end. You have to make sure that the tubes run to the right locations, but it fixed my problem.

 

Thanks for the good advice, i'll probably try to replace both pieces to be on the safe side.

 

Do you happen to know the GM part number for that vacuum disc assembly?

-Thanks

 

Valve Vac Sel GM part # 16032395

JamesC

 

Im dealing with the same repairs this week with my '91. My question is when should the line going to the heater control valve have Vacuum? With the heat on/off or AC on? Mine doesnt have any vacuum with the heat on/off. My AC needs charged again, slight leak, so I cant run it.

I did find that replacing the thermostat while I had coolant drained for the heater core replacement helped with the can running too cool.

 

does anyone know where i can get this part brand new i cant find it anywhere please help

 

If you still need part you can get it from NAPA. Part #207708. Cost around $27.00

 

i am having the same problem no heat. i have no vacum to the water valve. i used a maunal vacum pump an it wont hold presssure. is the valve bad? also i have only saw valves with 2 pipes in it mine has 3 is this normal?

 

I know it's simi unrelated but by any chance does anyone know if this is the same on the 4th gen I have this issue in my 91 firebird and my brother has got the same thing in his 95 camaro

 

Hi, guys!

I had a "hissing problem" in my HVAC, thought the problem was in right side rotary valve, those, which is controlled by upper control lever. But malfunction was not there, hissing was from left rotary valve, which is controlled by lower, "temperature" lever. I read a lot about valve repairing but in my situation problem was not solved neither with putting rubber for 2 hours in brake fluid, nor tightening the valve with bolt and nut.
As a result, i simply connected two hoses straightly with each other with the help of short plastic tube. And HVAC started working!

I attach a photo with brown tube inserted into hoses.


The question is: what for is this rotary valve, controlled by "temperature" lever in HVAC system? Heater works perfect without it. Now i have every position of blowing air working. Probably for AC?

 

Bolt and nut trick:

 

this is the repair most of you are looking for..the symptoms are the hissing,and always defaulting to the defroster...I have done this once and for all by using this method..this vacuum valve is a discontinued part,so use this method....

 

Did I miss something? Which method?

 

To Lasher...the post before mine has your fix...or this.....
http://www.youtube.com/watch?v=Mv782CIJDks

 

I'm going to try this aswell as my unit.

 

Ok guys I tried the brake fluid, and the nut and bolt trick, neither worked, I even went as far as taking the whole heater/ ac control unit out of my other 3rd gen( I own 2) and put it into the one I am having problems with, still the same hissing sound coming from the disc on the left, so I know the problem is somewhere else, something has to be hooked up wrong or something, any body have any ideas?? I'm literally stumped I have no other ideas of where to look, vacuum systems are my worst enemy...

 

not sure what you meant with brake fluid, but a majority of the vacuum leaks are shown/and fixed with the youtube version of the switch..see my post above..I have needed this a few times in the same car..but since they no longer make the part, we must fend to fix it this way ourselves..and works like a champ...Tow..after you tried to fix, does it still default to defroggers?....

 

What I meant my the brake fluid is I let the little rubber piece soak in brake fluid so it would swell, and yes when I took my whole unit out of my sport coupe and put it in my iroc it did the same exact thing, it hissed like crazy and air coming out of defrost vent and no heat. But i hook it back up in my sport coupe and it works fine, I'm thinking a vacuum line is hooked up in the wrong spot but I have no idea where to look or start

 

just read up on why you did brake fluid...ok....here's my thought..If its not too late to take pic of unit installed in your iroc(meaning with cellphone,and the connections behind the unit)..can you use that to compare color for color the hookup in the coupe?...Wondering if the years make a difference in the options..the hissing sucks ,and i hope you have some patience,before you start slinging tools around the garage!!...Hoping someone else will chime in with some knowledge...

 

Hey I'm having the same issue with the*Valve*Vac*Select in my firebird and I searched the part number and we'll it's discontinued so I'm not sure what I can do any ideas?

 

I have the GM 16032395 in stock. I was alerted by a customer that there was a need for this item. I've begun refurbishing and testing them. I will have the other mode selector valve available soon and on my web site.

http://www.top-downsolutions.com/ind...category_id=67

Lon Salgren

 

for vacuum hose to control

 

The video posted above by mys10v8 just saved me $30. The nut-and-bolt fix worked well. The rubber was in great shape. I used an 8-32 nylon lock nut and an 8-32 x 1/2" phillips head bolt. No more hissing! Thanks to all.

 

I did this a couple of years ago and it works fine.

 

I did the bolt to fix mine

 

wish i'd have read this entire thread before buying the refurbished part from lonsal yesterday. haha. seriously, glad i found his website, glad he had the part. will give it a go and if not, try the bolt/nut fix above.

EDIT: didn't know he was affiliated with the website until just now. found his website looking for the part yesterday (used gm part number referenced in this thread). just clicked on his link today and saw it's the same. not an expensive fix, just hope it works!

 

Thanks again for this thread, thanks for this forum! Glad I found it!

I decided to try the repair on the existing one last evening since I haven't received the one I ordered from @lonsal yet. I removed it, soaked the rubber in brake fluid for an hour, then put it back together with the bolt/nut vs. the clip. IT WORKS!

 

So I tried this modification and used all the same parts as described. Well, when I tried the slide, the nut was in the way and me being an oaf decided to keep pressure and broke the valve 'arm' that the selector moves to rotate the valve.

Now, the part is nowhere to be found...unless I want to spend $160 on eBay. I'd rather get a refurbished head unit.

My question then is, can I just plug the vacuum lines into a different model valve? I purchased one on Amazon hoping it was the right one but it is a little smaller and the vacuum '****' are not aligned the same.

Any help would be appreciated.

Thank you!

 

I think the vacuum hoses are all on one unit.. .so youd have to remove them individually since the one piece is the same size as the stock wheel

 

Thanks for the response.

I think I've decided not to cut the vacuum lines. I'll just get another control unit. I'm not sure what year the vacuum switch I bought is for, but it mounts fine but the 'wheel' has a smaller diameter and the vacuum ports are not in the same alignment.

 

Yeah, definitely don't cut the lines. I think I still have a couple of good Camaro head units and one complete valve with the fitting with the lines still attached if interested
Henry

 

I appreciate it. However, I ended up buying a control unit from a Trans Am since they have more bulbs for better illumination. The unit I purchased works and has the correct vacuum valve/switch. I built a custom bezel to be able to install an Android radio and I utilize my vinyl machine to produce a custom overlay for the ac head unit (so the grey Trans Am overlay will be covered). See attached image of my current setup

(for some reason the vinyl is rolling up on the right side, so I will have to use some glue or something to secure that edge).

 

Cool!

 

No, the vacuum switches are specific to these vehicles. The switch is used on several GM vehicles. Email or text me a picture of what broke. I can help you with a replacement. I can also supply the list of GM vehicles that used them.

Lon Salgren
Top-Down Solutions
626-369-0040
e: topdownsolutions@yahoo.com

 

Lon, I ordered a unit out of a TA to take advantage of the additional bulbs. It is in working condition and has the same vacuum valve (it is white instead of black).

However, if I have an issue I will let you know.

For reference, below are pics


of my valve and you can see the 'arm guide' is broken off. Picture 1: Is a picture of the vacuum line side; Picture 2) You can see where the 'arm guide' broke off (the three o'clock position of the valve).

 

Are there any available for sale?

 

I no longer have any, sorry


Lon