a/c comes out of defrost vents

usually when i am accelerating it happens, but it also happens any other time- but when i let off the accelerator, it blows back out of the vents- what could this be???

You have a vacuum leak somewhere in the system. Start at the vacuum cannister or ball under the hood and work your way to the a/c controls. there may also be a check valve in the system. Check this by trying to blow through it both ways. One way should be open, the other closed.

how do i find the leak

Trace the line until you see a crack or break. More than likely it is not broken if it comes out of the vent sometimes. If you can find the check valve check it first.

so i trace those 2 tiny lines coming from the vacuum ball located under the air filter, until i find a problem- is there a certain line i should check- is there anything else i should check for?

If you follow those lines, they lead to the a/c controls. Somewhere in between you will find the problem. There are really no shortcuts. Just time and patience. Good luck.

i will give it a try tomorrow- hopefully i will find it

Let us know what you find. Thanks.

hey did u find anything? i have the same problem with mine and i have traced the vac lines i still have to check if the actual duct work motor door is bad it may be leaking there my does it with heat and a/c let me know what you find

Would the check valve be between the manifold vacuum and vac ball, or between the ball and the controls, or between the controls and the vent door motors?

Also, what does it look like?

Thanks

In most systems I've seen, the check valve is between the manifold and the ball. The reason being is the engine pulls a strong vacuum at low idle, therefore giving you vacuum for the accessories. Under load/higher RPM, the manifold vacuum is lower, which would cause the accessories to function erratically. Therefore, the check valve closes to maintain that high vacuum in the ball and thusly keep the accessories working until engine vacuum returns.

man i have traced the lines from the vacuum ballto where they go- took them off and put them back on and so on and so forth- how do i figure out which line has the leak- is 1 of them more likely to leak than the other- 1 of the lines goes into the intake manifold, the other into an adapter below the dash- can i get the lines at an auot parts store- is there something else i should looking for???-where the hoses connect under the dash, there is a plastic thing that connects the inside hoses to the outside hose- is this a check valve- i need some help- it only does it when i am goin at a good speed, then i will let off the gas, and then it comes back through the vents- can some1 offer more advice- i have tried sprayin with starting fluid

I looked at the vac line (red) from the ball to the source (upper intake manifold) and the only items I found were hollow splices in the tubing. This leads me to assume the metallic coupler (about 1.5 inches long & screws in the manifold) on the intake might be the check valve. This coupler also feeds vac to the brake's vac assist assembly.

So, does the metallic coupler sound like the vac check valve or might it be plastic, much smaller, and located at a junction somewhere in the vac line.
Thanks for the help!

can somebody help