Randy's doggone HVAC thread...

[rcarlisle]

Ok, went out at lunch and listened to and felt what the HVAC boxes are doing.   If I move selector slowly, with fan ON, I have each position with fan on.   So that's good I guess.   When I go to VENT or AC, the fan runs and air comes out of the floor vents only.   There might be a whisper of air out of panel vents.  ON MAX AC, I can hear the change in sound indicationg the recirc door is operating.   Still floor air only.   ON flor, it's all floor.  MIX is mix, and DEFROST is all out of defroster vents.  The selector movement isn't as positive to each postiion as I would like, but each position does see to work in some way.  

So am I correct in thinking the vacuum motors aren't operating the door for the vent correctly?  Just trying to figure out where to look and what to look for. Fan is blowing air somewhere.  I am going to peek under hood for vac lines going in that direction.   Is there more than one and do any operate the panel vents or is that all under dash inside truck?

I have removed and reinstalled radio recently - I could have knocked a vac line off - I read that in some forum today.

I would like to minimize the nuber of times I have to dig into dash and trying to figure out where to go first.

If I can get this working, I may take truck to garage that did engine and see if they know more about underhood.   They did put everything back and even a new belt on compressor.  Or I may drop some AC pro in it.  Any reason not to?  Worked in a former company truck I used.

Thanks  

[kramttocs]

I'd need to sit down and read through your scenarios in more detail but check this out:

http://www.garysgaragemahal.com/hvac-systems.html

Go to the 1981 FSM Instructions tab and then the A/C-Heater System tab.
Scroll down to Figure 3. It has a really good diagram and table that will allow you to mark off what is working and what isn't.

[rcarlisle]

Good idea.  I have looked at it but getting confused without the actual stuff in front of me.   I'm dense that way sometimes.  

[rcarlisle]

And just that quick, I understand it a little more.   Panel door vacuum motor, blue vac line would seem to be where I'm having issues.  At least I know where to start looking.

Thanks

[kramttocs]

Great!  Let us know what you find.

[rcarlisle]

Didn't get to it last night - was checking backup lights (non working), and also noticed that the brake lights weren't working (probably not hooked up with trans swap).   Removed switch and it seemed to be working at random.   So after trying to figure that out, ended up having to run to town for a new one.   Which seems to be working.   That is some sort of voodoo switch.  Makes no sense how it works, being floating like it is.   I'm used to the solidly mounted switches.  

[rcarlisle]

Time to revive this and maybe others.   So the AC was fixed and works.   But only through floor or defrost, which I thought would work but turns out it doesn't really.   If I open a vent window, I can get enough air moving inside to cool it somewhat.   I did experiemt in my 2020 Kona by using only floor vents and same result - not cool enough - you need the air blowing ON YOU.   Or at least I do.  

So... looking at various threds here and FTE.  I think I want to remove the dash to do mine.  I don't trust the 40 y/o plastic to not bust on the dash.  I've looked the the diagram in the reference section.  I also saw a post where guy said he had his dash out in like 45 minutes.  

Take out dash pad, instrument, radio bezels, radio, screws for AC controls, glovebox.  Basically every screw I see, right?  Are there any impossible screws? Or just keep removing and jiggling til it all comes out?  I hate things like this because I'm afraid something will go bad wrong and replacements are hard to come by.  

I think once I get to the airbox I can manage the hinge part of the deal.  

Any suggestions or other posts to look at for removing the dash face?  

[kramttocs]

rcarlisle wrote

Or just keep removing and jiggling til it all comes out?  

Pretty much. There is a screw to the left of the radio opening that is a bit hidden. It holds the wiring harness in a vertical run right there.

With the metal frame attached, the dash is kept fairly ridged but still something to take your time with when removing.

If you drop the steering column down you may be able to unbolt the bottom of the dash (side bolts, parking brake, the two lower dash support rods, hood release), unscrew the radio speaker bracket, loosen the top side bolts for the dash, and maybe you could pivot the dash out enough to get in there. I haven't tried this so may not work or be much gain over just removing it completely.

[rcarlisle]

Thanks.   Your sig has a quote in it that I hope won't apply in this case.   I usually don't have issues taking cars apart, but after finding how brittle these plastics are, it gets frightful.

[Gsmblue]

I replaced the blend door on my Bronco without pulling the dash. It was tight but not as bad as i expected.

The blend door I picked up from Bronco graveyard, was not cheap. The process was a lot quicker than I expected.

I did scrap my knuckles a fair amount, but that is normal for me.

All in all, when i do this again on my F350, I won't pull the dash.

[Pete Whitstone]

I had similar issues when I started into my AC system, and also had to drop the dash. The thing I didn't realize was, the dashboard is in two pieces, the plastic fascia and the metal frame underneath. Well OK I knew that. What I didn't know was that the plastic fascia does not separate from the metal frame without the whole thing being removed from the vehicle first. So I spent a lot of time removing screws that held the fascia to the metal frame, but all I needed to remove was the few bolts that held the whole metal frame on. This is from memory but here is what I did:

1. remove the little piece of the dash that goes under the steering column
2. drop the steering column
3. Remove dash pad, instrument cluster, radio fascia (not the radio itself, or the HVAC panel. just the plastic cover over them that says "ranger" or "xlt" or whatever trim level your truck is)
4. Remove the two bolts near the base of the windshield on either side
5. Remove the bolts from the metal support bars that extend from the firewall to the underside of the dash
6. Two bolts in the kick panel area, one on each side. One side is visible without removing the plastic kick panel, one side you have to remove it to see the bolt. I can't remember for sure which side is which but I think you have to remove the passenger side.
7. I think you have to remove the 4 screws that hold the HVAC panel in place, so the dash can separate from it. But there is no need to remove the panel itself, it can hang there while you remove the dash from around it.
8. I removed my radio as well, but I'm not 100% sure that was necessary.

That was pretty much it, the dash came out after that. I'm sure I may be forgetting a step or two, but it should become obvious if I am. It really wasn't that difficult and didn't take as long as I thought it would.

So I did all that because I had visually verified my vacuum motors were all working - I could look under the dash and see the arm moving in the correct direction with each different setting of the HVAC panel. But what had happened on my truck was that one of the doors had separated from its "hinge". Wasn't really a hinge, but a thin place in the plastic where it could bend. So the arm was moving the door, but since it wasn't hinged, it was just kind of sliding back and forth instead of opening and closing. I later found those doors at a Bronco place for like $108 or so. But I didn't know they were available and didn't feel like waiting on shipping, so I repaired in myself. Crudely, but it works. More info in this thread.

http://forum.garysgaragemahal.com/Help-needed-with-HVAC-vacuum-harness-tp93801p93992.html