A/C blowing only out defrost vents
 

My 96 LT1 suddenly stopped blowing air out the main vents. Even when pressing the Auto and other modes it still only blows out the defrost vents. It blows cold but ends up fogging up the windshield. Has anyone experienced this or know what is wrong?

Thanks for your help!

RE: A/C blowing only out defrost vents
 

hhmmmm....i know that in chrysler productsthe somewhat archaic item used to control this is called a blend door actuator. it basically opens and closes certain little doors to allow for air flow to different areas, and it should be around the blower housing itself. on the cars that i have seen it on, it is comprised of little plastic arms. very well could be your culprit.

RE: A/C blowing only out defrost vents
 

Thanks for responding. I will look to see if that is the culprit. It worked when I first bought the car and then slowly started becoming difficult more and more over time until now it doesn't work at all. I guess at least it isn't the compressor. It still puts out cold air just on the windshield.

Thanks again for the help.

RE: A/C blowing only out defrost vents
 

let me know how that works out. like i said, on non-vettes it was called a blend door actuator arm

RE: A/C blowing only out defrost vents
 

I have the same problem with my 96. I've heard it's pretty common and that it is due to the vacuum controller. I bought a new one but havn't had a chance to install it yet....

RE: A/C blowing only out defrost vents
 

hmmm..so its vacuum and not mechanical? interesting.

RE: A/C blowing only out defrost vents
 

Yes, vacuum controllers used to control the direction of the air flow in the C4s...IIRC, you'll need to pull that dash off to replace it, but it can be done.

Mac

RE: A/C blowing only out defrost vents
 

Through my research thus far I was able to determine that it is related to the vaccum system....not mechanical. Luckily our Service Director used to be a Chevy Mechanic and he is going to help me with it. The only thing that doesn't make sense is that it suddenly started working again for a couple days and then stopped. Could it simply be a vaccum line disconnected, degraded or punctured? When I bought the car the key fob wasn't working properly and they had to replace the transmitter in the dash. I guess they could have damaged a line then.

I will keep you posted what I find out. I have to do something before it starts to really get hot.....pretty soon here in Florida.

Thanks for your responses.

RE: A/C blowing only out defrost vents
 

I have a 93 that was doing the same thing. It turned out to be the little plastic manifold for the cruise control and the ac. It is located under the fuel rail cover on the passenger side. It was cracked. I replaced it and the ac has been working fine for last two years. Dont know if that will help, but it might be worth looking at. If not at the plastic manifold, maybe one of the vacuum lines.

RE: A/C blowing only out defrost vents
 

c44me, if it comes and goes, it sounds like you could just have something that is wiggling loose and causing the problem, perhaps a vacuum line, or a fitting somewhere in the system?

RE: A/C blowing only out defrost vents
 

This is somewhat off the subject, but could anyone tell me the approx. cost of re-charging the AC system? My 89 blows HOT on every setting but OFF. Sound like a re-charging is in order? Or worse?

Rich

RE: A/C blowing only out defrost vents
 

it could be simply a recharging, but it could be a gross leak somewhere in the system, in which case, charging thr system wont be enough.

RE: A/C blowing only out defrost vents
 

C44me: Did you ever figure out your A/C vent problem? I'm curious to hear what the problem was and if/how you fixed it...

Thanks!

RE: A/C blowing only out defrost vents
 

I have yet to work on this problem. I will be taking it back in the shop in the next week or so. I will let you know what I find out. I am equally anxious.

RE: A/C blowing only out defrost vents
 

Hi Pal, I'm a recent new member so my reply is a bit dated but may be helpful to others. The cost of a recharge varies, but will be approx. $175. In the past 2 years, I have personally converted 4 cars from R-12 Freon to R-134 with conversion kits I purchased at Pep Boys for $36. An extra $10. for Refridgerant Solvent. I evacuated the system,[profesional & back yard style] and discnnected hoses to flush condenser, evaporator,& hoses with solvent & compressed air. Dryer & Compressor, Air-only, No solvent. Reconnect hoses & charge system according to kit directions. Everything you need is in the kit, hoses with quick connect fittings, adaptors, pressure guage, pressurized cans of R-134, lubricant. It took about 2 hours. First check that the clutch on the compressor is working before going to a conversion. My 89 Vette had R-12 originaly. A pound of R-12 cost $65. A pound of R134 costs $6.95. Cheaper to convert if you can do the labor. I hope this info. is helpful to someone. Regards, Mike If you need more detail, post it on this thread and I'll reply.

RE: A/C blowing only out defrost vents
 

Hi I own a 96 Vette with the LT-4 motor and my dash vents stopped working. I would get air from the defroster and the floor vents but the dash vents did not work no matter what mode I put on ( heater, outside vent. or air ). I took it to the Chevy dealer and they diagnosed it is as the programmer ( a unit behind the dash that controls all of the vacuum lines ). They put a new one in and now everything works great, but it cost me $1600.00. I`m not sure if I got ripped off by the dealer or not because the Orininal GM service Manuals that I purchased at Corvettes At Carlise diagnosed it as the programmer too. But who really knows ?

RE: A/C blowing only out defrost vents
 

When I was in school were taught that all vacuum operated climate control systems have an emergency default to the defroster when there was a vacuum leak. This was done for safety reasons, you can drive with no heat or air-conditioning but there are times that you cannot drive without a defroster. Normally when any system defaults to defroster only operation it is a vacuum leak, I guess other reasons are possible but I have never heard of them.

RE: A/C blowing only out defrost vents
 

My husband had the same problem on his 95. He replaced some sensor by the left headlight. He unplugged the old one and plugged in the new one. The sensor thingy cost him less than $10 from the dealer. It also fixed his cruise control problem.

Sorry I don't know much about the guts of a car (any car), but I can tell you when something isn't working right.

Michelle

RE: A/C blowing only out defrost vents
 

Just bought a '96 LT4 CE today, everything is great with it BUT the air blows only through the defroster vent. Boy was I glad to see this discussion tonight. Hope it's a simple vacuum leak or blendoor actuator. Will post an update when it's fixed.