1991 heater - air does not change with controls?

[Fairlaniac]

My 1991 has great fan speed but no air comes out of the floor, panel or windshield vents? I move the control but it seems to do nothing. I have a Haynes manual but it doesn't help much. I'm assuming a cable may be broke or something at the connection point of the cable and heater control? Any articles or pictures to see what I'm looking for? I dropped the glove box but where do I go from there? I was searching on the forum but must not have hit the proper keyword for a good post on the topic. Any help?

Thanks,

 

[Earl43P]

I don't know a 91 from a whole in the ground, but here's how the later years did it.
Bolted to either the plastic fender liner or near the firewall will be either a black plastic sphere or torpedo shaped vacuum reservoir.

Follow the vacuum lines that go to/from that reservoir and make sure there are no cracks, splits, melts or breaks in those two lines.

One will route from the engine vacuum port TO the reservoir (also called an accumulator) and the other will come from the reservoir to a connection at the firewall. I'm guessing that is where you will find the problem, a broken vacuum line. If you don't find anything wrong with either line, perhaps the reservoir itself is cracked or split. It should hold a vacuum even after you shut off the engine.

For example, after the engine is off, you should be able to select vent or floor and hear a door/damper move inside the heater box under the glovebox.

I'd be surprised if it isn't as I described, but who knows if the earlier years had a mechanical cable to open the doors/dampers. I kind of doubt it though.

 

[adsm08]

I think the 91 still had cable operated stuff. I don't think the stupid vacuum crap started until 95 when they changed the dash for the last time.

You probably broke a cable or a door. If you can take the dash pad off it will all be laid out right in front of you to see.

 

[Fairlaniac]

This is my under hood look of heater

This is an A/C truck, when the ignition is off I can hear air when actuating the heater controls. I am use to older cable controls. Would mine be cable controls or something else?

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Thanks,