[berkdog84]

I have a 92 5.0 fs bronco.

the other month my a/c system got stuck in defrost mode. no matter the position of the switch it stays on defrost. A/C will still blow cold but only blow on with window. same goes for the heater.

I searched and found that people suggest its a vacuum line issue. Could someone please provide pics and/or specific locations of where these lines i should be looking at are.

thanks

P.S. I love the suggested related thread feature when u start to post a new thread! even better than searching!!!!! :thumbup

 

[dan50]

The linkage and the vacuum operated actuator are circled...

 

[berkdog84]

thanks for the info!
very helpful and precise

so i checked there and the line is in fine shape. nothing look out of the norm even soap and watered it to make sure there were no leaks. so now what?

EDIT: ok after poking around some more on the forums its suggested to look at the line that is hidden under the wire loom. so i shall do that tomorrow

 

[dan50]

Does the actuator move when you hit it with vacuum?

 

[berkdog84]

how can i test it? do i need to pick up a little vacuum hand pump from autozone?

 

[dan50]

Well you can physically move the lever to see if the actuator is locked up for starters.

And then you can start the truck (to get a vacuum source), and run a new line from a known vacuum source to the actuator.

Or you could buy a hand pump. Never used one.

 

[berkdog84]

ok moves by hand just fine i shall test out with a vacuum source soon. btw once the white line vanishes into the finder how do i catch up to it again (were dose it go)?

 

[dan50]

ok moves by hand just fine i shall test out with a vacuum source soon. btw once the white line vanishes into the finder how do i catch up to it again (were dose it go)?

White line?

Fender?

You lost me.

If the actuator isn't the problem, it is next most likely to be the HVAC controls themselves.

 

[jhjones84]

I'd check the knobs inside the truck my temperature one goes around and around without changing the temp

 

[petlover07]

On the newer broncos, there are colored plastic lines that go to that vacumn actuator. They could be white also. they get very brittle when they get old. they will be hard plastic lines that go to the vacuum canister and possibly away from it. I had to replace those lines with rubber hose when it did the same thing.

Just look for some exposed white or colored plastic looking tubes. If you fiddle with them, they will most likely break apart, then you can follow the line and replace it with rubber. You can't get those lines replaced with original, for obvious reasons.

I would send pics of mine and where they are, but my bronco is being stored right now. So here are the pics from above with the areas circled where you might find these lines. (in my next post)

 

[petlover07]

ok, well that copy/paste/circle/paste didn't work as easy as I thought.
oh, you white line goes into the fender? Is it about as big around as a pea maybe? 1/4 inch? That line should come out and connect to the vacuum canister (a ball or coffee can looking thing on the passenger fender)

 

[DezertBronco]

Mine has the exact same problem, its a vacume line under the dash.:doh0715:

 

[bergs]

i had a vaccume line knocked off behind the dash, take out the ashtray and ac controll panel and the glove box and see if you can hear a leak or see a tube that is not connected. mine was a yellow hose behind the ashtray that was knocked off of a vaccume actuator. i put it back on and was good to go.

 

[ANUBIS]

Thank God I found this thread. My a/c has been pissing me off like a crazy. It blows cold for a while until all of a sudden it starts blowing in the defrost mode. I looked at that white plastic line and when I gently touched it it crumbled in my fingers, lol. I guess I know the source of the problem now :doh0715:

 

[JohnMcD348]

How's the easiest way to get behind the dash on a 92 Bronco? I have the same issue that just cropped up with mine.

 

[ANUBIS]

Anyone have a part number for this vacuum line? Or have a part number for something a bit more durable than the original whit plastic one that is too brittle.:thumbup

 

[petlover07]

replace with rubber line

 

[ANUBIS]

Okay here we go again. Sorry if you think I am lazy but to me it makes sense.

I know I have to replace this little b.s. line with a rubber vacuum line. I can see obviously where it connects in the engine compartment. But does anyone know where it connects to after the fire wall? I really am avoiding tearing thru the embilical cord like cable just to make more work for myself later sorting it all back to the way it was.

At least if someone can tell me where it leads to (possibly with a pic) then I can just run the line and leave the old one to continue it's rotting until it's gone.:thumbup

Thanks.

 

[ANUBIS]

Got to checking where this infamous little vacuum line runs off to, and I think I have found it. Could anyone confirm that this is that right one? My manual does not tell me shite! :doh0715:

White vacuum line:

Embilical that it runs into:

Where it runs into the FireWall:

Found it behind the glove box:

This is what I found running from the direction of the firewall:

Can anyone confirm that this is the right one?

Thanks:thumbup

 

[tripleh87]

my 87 is acting like this, been like this for awhile. panel vents work fine, switch to floor, panel vents are still on, switch to mix, floor vents come on, switch to defrost, mix comes on. this is probably what i'll have to look into, just don't want to have to tear the whole dash apart to fix it. my bronco is in my barn, not too road worthy at the moment.