Ive got an 84 Fiero SE with AC. Since it was a little chilly the other morning I went for a bit of heat. Got plenty of heat....but its blowing in my face thru the "ac vents", rather than coming out at the floor.

I cycled between Heat, Vent, AC and Defrost several times. I can get air from the "ac Vent", and I can get air from the dash "defrost vent", but nothing at the floor.

I did a search and saw people who ONLY got defrost vent, and in this case they clearly had an actuator that was not work at all OR they didn't get any heat at all which appeared to be a problem with the blend door. Since my problem is a bit different, I'm not sure why I can switch between ac vent and defrost vent, but not the floor vent.

Any ideas?
Thanks

According to my 86 factory manual for air delivery you will need to look at your mode door actuator and linkages as the probable cause for your heater vents not working.

The mode door controls your defrost, vents, and heater outlets. It is a motor that rotates a mechanical linkage set which opens, close, or partially opens two doors in the air box. The Mode door separates the vents from the other outlets. The heat/defrost door controls the air to the defroster and the heater outlets.

I have attached scans of my manual which shows operation of the system, troubleshooting the actuator, and basic operation of the system.

I suggest that you first check your linkages from the actuator then check power to the actuator that is described in the manual. I would use a multimeter instead of a light to check power between the pins during the check.






hope this helps out

edited to add another manual page and clarity

[This message has been edited by Tanlrat (edited 10-05-2008).]

Thanks Tanlrat, That is very helpful. Looks like a single actuator is working two different doors (defrost/heat and ac/vent).

Do you know if that mode door actuator connector can be reached from under the dash to perform those tests, or does the dash have to be removed to even do the test?

Since the ac/vent door is working, do you think its safe to assume the actuator is fine and problem is the mode door linkage?

You may be able to access the electrical connector only with out pulling the center console. I haven't screwed with the air box since i had to replace the heater core, which is under the passenger part of the dash. The rest of the box is behind the center console. It will be rough but at least you know where to look. My money is on the linkage.