MaddMaxx

The AC will not blow out the front vents, but blows out the floor and defroster all the time. I have checked archived threads and would like to check for a vacuum problem but do Not know where to start. All help appreciated...Tampa is heating up!!

Thanks in advance :mad

Aggravated4life

We have different year cars but Im guessing its the same problem.Theres usually a vacuum plastic check valve that goes bad.Its located on the rear of the intake on the L98's and on LT1's its located on the intake under the plastic cover somewhere.
Sorry cant be more specific but thats usually what causes the problem you described.If you have the repair manual it can help locate the vacuum parts.
Thats where id start.

85alusion

I have the same problem. Blows out everywhere but front. I have no leaks. Keepem comin boys.

PurpleC4

Plastic vacuum tee under passenger fuel rail cover
One of the most commonly overlooked, yet easily recognized vacuum leak occurs with a plastic vacuum “T” under the LT1 passenger side fuel rail cover. Located about mid-way between the front and back, and situated very closely to the top of the intake manifold, the “T” is subjected to enormous heat.
Visual inspection often doesn’t reveal that the vacuum “T” has failed. The vacuum “T” tends to slowly disintegrate over a period of time. The best method for inspection is to actually turn the “T” over and look at the underside. What you find may shock you. Due to heat, the “T” fitting actually decomposes on the side toward the intake manifold and develops large holes similar to Swiss cheese. Replacement is cheap and easy.
GM calls that vacuum “T” a "valve". The GM part # is 14056648. You can pick one
up from your friendly Chevrolet parts man for cost + 10% + tax = $3.00
If you don’t have easy access to a dealership, you can call Superior Chevrolet 1-800-728-8267.
:seeya Purp




[Modified by PurpleC4, 7:40 AM 5/16/2003]

MaddMaxx

I think I may have found it. There is a pencil sized rubber tube that runs from the top of the (air duct, coupler) towards the pullys and front of the engine. This line appears to have been nicked a few times by the belts or pullys. Bad news is when I took off the fuel rail covers, I noticed pooling oil on the driver side above? the valve cover. I will replace the tube and get back. Any ideas on the oil?

Thanks max :)

MaddMaxx

I taped the cut line to see if it made a difference and then found a major leak coming off a rubber elbow dead center on the manifold drivers side. Temporarily taped that one also to see if would help. Nothing. Still will not blow out the front vents at all. It is cranking out the floor and defrost?

MaddMaxx

Fixed the PCV elbow and the nicked line, but the air still does not blow out the front. Went to autozone and they pulled a p1416 code and lean mixture code. What next?

Caliburn

I had the same symptoms last year - mine turned out to be the AC Programmer - a couputerized box that controls vacum switches for the auto AC models (I am guessing you have auto AC). I don't have my manual with me, so I don't remember how, but you can pull codes from the auto AC system (but when my programmer went out it did not store any codes). The thing is located on the firewall above the pedals - not the easiest thing to get to. Also not the cheapest thing to replace, either. As I was reading the posts, I was hoping you would find an obvious vacum problem before having to consider the programmer.

Heath

PurpleC4

http://forums.corvetteforum.com/zerothread?id=561971

abrase

I just took mine into the shop for the same problem. The vacuum valve was clogged and needed replacing. $97 parts and labor and the A/C works great now. :steering: