A/C blows out at bottom and defrost instead of vents....


Slick 86 T-type
Im tryin to fix it before summer........i can turn my A/C on and it will blow out of the bottom and at the defrost instead of the vents anyone have any suggestions.......
There are a series of clear (yellowish now with the age of the car) hoses that work on vacuum. Make sure you don't have any holes in them and that they are all connected at both ends. I also think there is a switch on your heater/AC box. Make sure that is functioning properly. I have a similar problem in that it takes over a minute for mine to switch to the vents. I have not checked my switch yet.
Check the vacuum hose (small, about 7/32") in the engine compartment. Probably not getting vacuum inside the car. No vacuum=air out the defrost vent. Look over near the blower motor and follow the line back to it's supply point.
After you check the vacuum lines if it still doesn't work your vacuum switch is bad.

Remove the trim around the radio HVAC controls and then remove the four bolts holding the HVAC controls to the dash. The whole assembly will pull out and you will see the vacuum switch that spins around when you move the lever.

The part is available at your friendly neighborhood GM dealer for ~$20.

If you do a search you can find the part number, I posted it a while ago.

Good luck!
There is a heck valve under the hood that is there to prevent boost from damaging the heater vent controls. Check and see that it is not popped. If it is, then you probably popped one of the diaphragms that operates the vents. My guess would be that it is the one near the floor just to the left of where the heat comes out onto the floor. That is where my popped one is. I tried getting one from the dealer, and have been waiting a couple of months for it. They charged my card, and now they've changed hands. I wonder if I'll ever get my part or money back. Anyways, pull the vacuum line off and check to see that it holds vacuum. If not, then you have found your problem. If it does, then as mentioned earlier, it could be the selector. Good Luck, and let us know how it turns out.
i had the same problem and it ended up being the a/c heater control panel thing that you switch from a/c to heat to defrost was bad..in the back where all the vacuum lines go there is a gasket and it was wore out along with the clips that hold it tight...i got a new one for 50 bux...
If you have changed any vacuum hoses under the hood DOUBLE-CHECK that you have replaced the check-valves in the right direction! :eek: I forgot... I mean a friend of mine :rolleyes: forgot and had the same problem; the check-valve on the backside of engine controls vacuum to the a/c controls.