I recently bought my vette and having troubles with the direction of the heat. The fan blows hot air, but only at the foot area. When I select vent or defroster, it doesn't blow any air in that area, only in the floor no matter what I select.

I had a friend tell me the doors are probably stuck in the floor section and their is probably a vacuum leak that will not move the doors in the right directions.

Is this true and how can I check to see what's wrong?

I would like to fix it myself, but don't even know what to look for.

I could use any information anyone can give. Thanks!

 

vacuum troubleshooting

Try here, very detailed help, easy to follow instructions. Unfortunately vaccum issues on vettes are common place. By a decent tester/pump from Sears or someplace similiar, it's worth its weight in gold. I had a similiar problem to yours but it only did it after I turned on the headlights. Look for doc rebuilds website, he's in Connecticut, he has all the kits you could possibly need to repair your vac system. If you cant find it let me know and I'll post a link for you, keep us posted.
ESU

 

On at least later C3 the problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine is damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease or vasoline to fix.
3) If you have a heater, the small vac. tube to heater hose valve underhood probably also needs replacing. Block w/o heater.

PS The design problem comment is not intended to be offensive to any of our northern friends.

 

The heater/AC controls are usually two stage. The hot/cool lever is usually a cable and opens and closes a door in your heater core box. The lever that contols vent, defrost,floor etc is usually vaccum operated. The switch directs vaccum to various doors and opens and closes them.

I had similar problems. It turned out to be my control switch. the easiest way to check will require some dismantling. but you maybe able to get at it without taking too much apart. Take your consol side panel off. You should be able to see the switch. Make sure the vaccum lines are all connected at the back...they are all attached to a circular looking thing that plugs into the switch.

If they are plugged in...do you hear a hiss???Vaccum leak? The switch has an internal part that directs the air to the various vents. There is a funny looking washer that holds this assemble together. This washer sometimes falls off. If it has you will find it in the vacinity of the switch. You can reinstall it..don't loose it ...they are hard to find. It took me awhile to find one in a scrap yard...I believe it was out of the heater control for a late 90'2 GMC van. You can also start the car...apply pressure (slight) to the rear of the switch with one had and move the control with the other...the vent may change...if it does its this internal part thats not functioning.

If all is okay with the switch you will need to follow the vaccum lines to the 2 or 3 vaccum activated vent doors. the problem might be there.

Jim

 

Thank all of you for your suggestions. I will try them and see if anything works.