No air blowing out dash vents

[Nish Limaye]

Was 108 F today, course car decided to have a/c problems. 87 GN with "manual" airconditioning. Problem is that I do not get any air coming from vents when lever is in Max, Normal positions. Cold air comes out defrost and floor vents only.

Hope someone has some trouble shooting ideas.....anything I can check on engine side of firewall or does dash need to start coming out...?

thanks
Nish Limaye

 

[Steve Wood]

Doubt the dash needs to come out.

1. There is a cable that runs from the top lever of the ac/heater control head to an arm that opens and close a door in the heater/ac ducting under the dash on the firewall (in the passenger compartment). Open the glove box and then drop it down so you can look thru the opening at the heater/ac box. Move the lever back and forth and locate the other end of it. Make sure it is still connected to the arm in the box and that the tip of the arm did not break off.

2. If that is not the problem, look under the hood and make sure the hard plastic line that runs across the firewall to the passenger side is not broken. Also check the line that goes to the heater water control is connected..then check the lines that to to the firewall along the drivers side, to the vacuum reservoir ball, etc...to be sure there are no leaks.

3. If everything is solid, then suspect the vacuum control switch on the back of the heater/ac control head. You have to pull the head out and check the switch. It tends to fall apart with age.

 

[digorok]

Check the past post

Two readers had the same problem a few weeks ago. Lots of good information and a few fixes. Try doing a search or just go back a few pages.
Seems that the systems are starting to wear out and giving problems.

 

[Turbo Dog]

I had the problem described in Steve's #1 scenario about a year ago. The dealer still had the plastic part available at that time.

 

[PaulRV6]

Yes good responses. The plastic control switch is GM 16037778, cost about $15.00.

paul

 

[needforspeed]

Originally posted by Nish Limaye
Was 108 F today, course car decided to have a/c problems. 87 GN with "manual" airconditioning. Problem is that I do not get any air coming from vents when lever is in Max, Normal positions. Cold air comes out defrost and floor vents only.

Hope someone has some trouble shooting ideas.....anything I can check on engine side of firewall or does dash need to start coming out...?

thanks
Nish Limaye

I just had the same promblem not too long ago,I found a vacuum leak in the engine compartment back along the firewall.I repaired the vacuum leak and PRESTO I had the A/C blowing out the vents.

 

[TurboTer]

Similiar problem

I have almost the same problem, except sometimes it actually works if I fiddle with it long enough. Also, let's say it is working and I shut the car off while NOT moving the a/c switch from max to off (or whatever). When I start the car again (even if a day or two later), it will still work fine. But when I move the switch to off or defrost (or whatever), then back to max, it won't blow out of the vents again until I fiddle. Any idea what my problem is? Switch?

 

[digorok]

Sounds like switch

The switch/vac control is made really cheap. It's all plastic, has a thin rubber seal that tells the air where to go. With time and moving it to change vents, it will wearout. They use a grease to help it seal, and the grease gets hard and causes more problems than help. Wouldn't be surprised if most of them are leaking or pluged up by now.
You can take it apart to clean and reseal. Sometimes works sometimes not. Might be better to just change it.
You can still get the control from the dealer or auto parts store.

 

[PaulRV6]

Sounds like the control switch to me too. Mine would work sometimes and then it wouldn't. Easy to change, did it last nite and took about 20 min. or so. See above response for P/N.

paul

 

[TurboTer]

Re: Sounds like switch

Originally posted by digorok
The switch/vac control is made really cheap. It's all plastic, has a thin rubber seal that tells the air where to go. With time and moving it to change vents, it will wearout. They use a grease to help it seal, and the grease gets hard and causes more problems than help. Wouldn't be surprised if most of them are leaking or pluged up by now.
You can take it apart to clean and reseal. Sometimes works sometimes not. Might be better to just change it.
You can still get the control from the dealer or auto parts store.

What do I reseal it with? Also, about getting the control from an auto store: Are you talking about one little part or the entire air conditioning/heat panal above the radio? I just removed the whole thing and put another one in. Unfortunatly, the one I replaced it with didn't work at all (even on high, you can barely hear the thing; any ideas?). I cleaned my old one, put it back, and same problems.

 

[digorok]

Vacume switch

I normally just change the vacuum switch. Went through all the work to remove it and don't want to do it more than once.
They call it the vacuum switch, I think it should be called a vacuum control. It's the round thing that all the vacuum lines go to, it kind of looks like a spider. I've been told that they sometimes are made of metal, but everyone I've seen has been plastic.
You should be able to get it from a regular auto parts store. I think the GM number is 16037778. The 4seasons number is 36694.
Check the system to see if you have good vacuum to the violet hose with the engine running. If you do, the switch is probably leaking. If no vacuum, you need to trace the line and repair the leak.
Send me your email and I can send you a vacuum diagram.

 

[TurboTer]

Well, I had access to another used whole (the entire thing above the radio, not just a little part) A/C control panel out of an Oldmobile (I think). So I put it in, turned on the car, put it on max, and it worked. I got all excited. Well, then I shut it off, and put it on defrost. Now, defrost worked perfectly. But then I put it back to max and it stayed on defrost! I shut it off, put it back on max, and it's still on defrost! I didn't seal it with anything, and this unit was used too, so maybe it's still the switch? I have to buy a new one.

 

[PaulRV6]

defrost mode ????

When in the defrost mode, I do not get any air out the side vents, only the top dash vents? This doesn't sound right to me cause my side windows were not clearing.
Also, what would cause my windshield not to clearing very well? I had the windows all closed cause it was raining hard so the windows were fogged pretty good. I even had good air coming out. Is this A/C suppose to come on or something? Thanks

paul