AC/Heat control failure 95 Suburban

[JD]

Today was a nice day here and I decided to turn off the heat and turn on the
vent. No matter where I set the control, it still blows air to the floor.
My thinking is the door is stuck or a vacuum hose has failed.
Before I take it to a dealer I'd like to try and fix it myself. I looked in
the engine compartment and could not hear a vacuum leak nor did I see any
dangling hoses, but I didn't really know where to look. I tried banging a
bit on the box below the dash board and that didn't seem to dislodge the
door.
Any help on where to start would be appreciated.
Thanks
JD
Chesapeake,VA

[Curmudgeon]

Had the same problem with my 95 Blazer. It was the vacuum motor that
control the underdash flaps. In the blazer they had to pull the ENTIRE
dash to get to 'em. NOT cheap, I'm sorry to say.

"JD" <ja...@yahoo.com> wrote in message
news:kn67c.19144$Cf3.3622@lakeread01...

[Curmudgeon]

One other thought. On the Blazer, the vacuum resevoir tank is mounted to
the hood, at the back end closest to the firewall, on the driver side.
Check it and the hoses going and coming. Also, there is a vac check valve
in the line close by. Take it out and suck on the end farthest closest to
the resevoir tank. If air comes thru, you got a bad check valve, and that
could be your problem.

"JD" <ja...@yahoo.com> wrote in message
news:kn67c.19144$Cf3.3622@lakeread01...

[Alan Shinn]

Just fixed the A/C on my '95 1500 a few days ago. After a lot of
searching, I found the attached message on www.chevytalk.org forums...
His description of symptoms matched mine except that I have no rear
defogger. Since my controls weren't exactly the same, the transistor
wasn't quite as described. Maybe this info can help you, too.

On www.chevytalk.org, search the forums for "a/c problem fixed" from all
posts and you should find:

* a/c problem fixed
* #348460 - 02/26/03 07:38 AM
*
* Hi there!
* I hope this info is valuable to someone perplexed by defect a/c.
*
* If you have following symptoms in your truck
* 1) A/C button won't work
* 2) Recirc won't work
* 3) Mode of operation knob has no effect (air comes only to floor for
* example)
* 4) Rear defog button works normally
* 5) Temp and fan speed knobs works normally
* then you might have a similar problem I had. The fix is both easy and
* inexpensive. Culprit is bad transistor Q1 on your control head. By
* changing it (cost: 6 cents at Radioshack) everything works as usual.
* Here in Finland GM dealer asks 275 Eur (about same in US dollars) for
* the head, so there is your motivation to fix it by yourself.
*
* To take the head off, remove dash and gently slide the head out.
* There are clips on both sides of the head, you need a screwdriver to
* tweak them slightly inwards. Disconnect all cables.
*
* The transistor is MPSA56 (bipolar pnp) and you can locate the faulty
* one easily. It is the one under the bracket just next to mode of
* operation knob axis (NOT the easiest one at the edge of the board).
* Install the new one to the other side of the board, so you don't have
* to fit it into that extremely confined space. Make sure to connect
* the legs to the right holes. Emitter, base and collector are marked
* on the faulty transistor.
*
* If you have anything to ask, contact me and I'll send more
* descriptive instructions.
*
* jari
*
* -----------
* Suburban -97 6.5TD, 73000 mi

-alan