Blend Door / No Heat questions

Hello, I recently purchased a 1999 Bravada. It ran great for the test drive!!

I've been coming here for info and after rebuilding my transmission, I find that there is no heat.

I checked the blend door posts (what I could find) and I THINK this is the problem.....

I took the glove box door out of the way and turned the heater knob back and forth and didn't see or hear any movement from the blend door or the aluminum arm I presume is connected to it.

The VAC unit didn't seem to do anything, either. I disconnected what appeared to be the vacuum tube and it didn't seem to have anything happening, either.

The thread that shows the pictures of how to remove the blend door motor on a 98 Blazer are a little different on my 1999 Bravada. I have a major duct going across it, severely limiting access.

Before I get too far involved, I'm wondering what, exactly, powers the blend door motor? I've already checked Fuse #21 in the side of the dash and the HVAC under the hood.

is there anything else I could/should check?

BTW, I did find bare wire in the bundle that goes along the vac unit. A blue wire is jumped to an orange wire. Any clues on that one?

Thanks !!!

David in OK

Anyone ??

Welcome, David in OK ! This is David in OK, also ! How am I ? :D

I didn't want you thinking that no one here was going to respond to your post/plea for help...........even tho that's apparently true!!

Here's what I found: The blend door actuator is bad. I bought a mini-ratchet that bends to 180 degrees. I ground off parts of the socket, ratchet bit (what the socket attaches to) and the handle to get more degrees of movement. It worked pretty good for the screw on the right. The left screw didn't pose too much of a problem, once I got it loose. I finished removing both using the socket on the screw by itself.

Alas, that stupid gear was broken big time.

The orange and blue wire were part of the harness going to the actuator. I speculate that a previous owner, in an attempt to "fix" it by bypassing a switch jumped those two wires together. It didn't work, as that wasn't the problem.

A few phone calls, I find NAPA has it.....or so they said, for $49. I took the original down there and noticed their replacement didn't have screws holding the halves together. Instead, it had tabs.

I also noticed that the pins were not alike. As someone else posted, they got the wrong unit. (the manual one as opposed to the 'auto' one that I needed)

The clerk allowed me to take the unit apart ( !! ) so I could study the innards.

The main gear was entirely redesigned. No longer did it have a metal center post, but it was a one piece affair. All well and good, but the "stop" that was on the metal center post hit the bottom of the unit on the outside.

The new one.........has the stops on the INSIDE.

This meant that I could not simply swap out the broken gear.

Upon further study, I concluded the rest of the internals were identical or close to it, so I thought I could swap out the old circuit board to the new housing, utilizing the improved gear, so I bought the unit, knowing it was the wrong one. They told me that I'd have to go to a dealer for the correct part, which from other posts I know sells for $180. I decided to take a chance on this one. The clerk gave me $3 off as a result.......(hey, it beats a poke in the eye !)

Once home, I discovered that the two housings are very similar, but have enough subtle differences as to test your patience pretty well. I finally figured it all out and it snapped together just fine.

I hooked it up before installing it, having the temp all the way 'cold' then turning on the ignition. I turned it off, moved the knob all the way to 'hot' and did it again. It appeared that the gear wasn't moving as far as I thought it should, nowhere near the full range of motion allowed by the stops.

I reached under the dash and moved the blend door by hand and it seemed that the range of movement agreed, so I put it back on.

By this time, my fingers and the socket were slippery, mostly from the gear lube. I degreased it all and sprayed some "no slip grip" (can be found in weight lifters aisle at a sporting goods store) and I was able to finger tighted things just fine. I could even feel the screw seat on the last turn. It's amazing what a non-slip grip can do in tight spaces.

I tested the "Auto" air and it worked PERFECTLY ! :iceslolan

I got the wife, and she joined me for a ride in the repaired chariot.

I hope that this post can help someone else, as it appears you won't get much, if any, response to this issue anymore.

.

Hi David, sorry about the lack of responce but this forum has for the most part been asborbed into the Blazer/s10 forum so that the advisors don't have to many threads to keep track of. You might try posting and searching there for common problems.

Great description on your diagnosis and fix, I'm sure it will be a help to someone.

And I'm going to have to find some of that "no slip grip" stuff, sounds like something I could use.

Moving to the proper forum (as stated in the sticky at the top of the forum).....