I have a 1990 bronco and the floor vent does no blow out
all the other positions worx except for flr/dfrost floor
wont blow on my feet any body got any clues

 

I'm having the exact same problem - mine was working up until a while ago..... the only thing I've changed is to plug in my A/C (it was unplugged by a previous owner). I'm wondering if it has something to do with it or not.

Pooks
1990 Bronco XLT 5.8L (Casper)

 

ventilation problems can stem from vacuum hose problems. i would start at the vacuum tree. when you lose vacuum to the selector panel, the system seems to blow all the air cold/warm thru the defrost. maybe you are dealing with a lazy vacuum motor under the dash.

 

this is cause by a rotted or cracked vac lines. the most common spot is under the hood to the left. you will see the lever that controls the air routing. look at all of those different color plastic lines.

 

The ventilation system gets its vac supply from the hard vac line that runs thru the plastic just above the blower motor by the R hood hinge. There's a second one coming out to the fresh/recirculate vacuum motor, but they're the only 2 there. There's another underdash vacuum motor that you can see from the passenger footwell that controls the footwell registers, and another that you can only see by removing the glovebox that selects dash/defrost.

 

I've got the same problem on my 91 Bronco. I can set it on vent and it comes out the dash vents, if I set it on defrost it comes out the windshield vents, but if I set it on heat or floor/heat it still just comes out at the windshield but not the floor.

I haven't found any vacuum leaks and both of the vacuum actuators seem to work fine. I would think if it was a vacuum leak it wouldn't switch between defrost and the dash vents either. Where is the actuator that moves the flap to make it blow out at the floor? When I move the selector lever on the heater control from vent-floor-flr/defrost-defrost I don't see what is controlling the air flow.

 

The default location for the system is out the defrost vents at the windshield. No vacuum is required to make air flow from that location. It is a combination of vacuum-driven dashpots that move the two dampers in the system (located near the center of the dash and up under it) that force air out the other two locations. If only one of them is working or has vacuum then you would get a situation like the one you have. My 92 had a similar problem once and the seam on the one dashpot had ruptured. I had to go digging for a replacement in a salvage yard. Fortunately, the F-series trucks are identical so I didn't have to find a Bronco to get what I needed. This is not to say that your issue is the same one but that is what happened to mine.

BTW nice use of the search function. Not often I get to see the posts from the old timers anymore. Steve83 was a tremendous asset to this forum for a long time.

 

greystreak92, good to hear from you as well. I've not been on here lately as I have way too many other irons in the fire as they say. I can see the one vacuum damper on the right side of the heater box behind the glove compartment and another under the hood on the right side. Both of them seem to work ok. You say there's one in the middle of the dash? Can I see it if I take out the radio and heater control?

 

Yes, you should be able to see it with the radio/climate control head out.

There is some thought in the back of my head that keeps popping up about a blue vacuum line with a clear connector up under there that gave me a bunch of grief as well. I could just be crazy too but I just keep recalling some issue with a blue vacuum line.