96 Bonneville A/C problem changes vents when stop

Ok another one of these crazy A'C problems I works when it wonts to It has the ECC type in it I have had some trouble i the past and it went back to working but has decided to do its own thing again If i put it on the Auto clamate it only blows out the winsheild vents so i use the manual setting to make it blow out the A/C vents but now whem we come to a stop it will start blowing out the winshield vents untill we get going again I notice that if i have the temp set on a certian degree and then turn it the unit off while driving and the cut it back on it resets to 60 degrees and blows out the top vents again and it if i have the maual A/c working and push the recirculate it starts blowing out the top vents again could it be that the control panel has gone bad or is it worse thanks for any help

The airflow is directed to the defrost vents by default in the event of a vacuum loss. Usually I would tell someone in your position to check the vacuum line going to the reservoir (vacuum tank) under the hood but I don't think you have one there. The vacuum source for the climate control may come from the brake booster. What you need to do is inspect the vacuum lines for cracked, brittle, broken or disconnected lines or connectors. I believe there is one that runs along the firewall from the grommet behind the passenger's side shock tower towards the brake booster.

thanks for the info i will look and see but is there a chance that the ecc controler is bad too thanks again

I wouldn't think it is the problem. these cars have their fair share of common electrical problems but the HVAC programmer and ECC head are not known to be a usual suspect. they both are pretty reliable.

I have finally discovered the location of the vacuum reservoir, at least for a 97 but it should be in the same spot in your 96. It's located "behind the right front fender" says the factory service manual. Since the removal instructions to not say to remove the inner fender, I'm willing to bet that it is forward of the RF wheel, kinda under the battery. It will look like a big black plastic jelly bean. Check the vacuum lines to and from the tank for broken or dicsonnected lines.

ok i knew it was there and every one keep saying the vaccum came off the brake booster and i never found it and it was driving me nuts i got to take time and taer it down ti see if thats the problem will post back when i check it out thanks again