h/ac vent control

I have an 89' SHO without climate control. The car has a fan/blower vent control on the dash with settings of max, norm, vent, off, floor. mix, and an icon. My compressor went out at the end of the summer. Up until then all vents including at the back of the dash on top, on the dash front, and on the floor were working.

When it got cold enough to use the heater from time to time, I noticed that the control does not seem to work now. When I turn on the heater and fan/blower, all settings seem to result in heat from the back of the dash on top. None of the settings result in heat from the dash front vents or the floor vents. The fan/blower seems to work well at all speeds.

I'm hoping that fixing the compressor will resolve this. Any guidance on this will be appreciated.

Cliff Tussey in Kentucky

 

try doing a search on "blower control module" in this section

 

I did that search and it brought up maybe 8 posts about the BCM, but they were not about my situation. ct

 

try a search for "blend door actuator"

 

Got some stuff there. The first post suggested a fuse. It will take me awhile to go through this. Ill be back. ct

 

Your problem won't have anything to do with the bad AC compressor.

Even though you have a manual heater, not an EATC, the vents are still controlled by vacuum pumps. So the first thing to check is that the system is getting a vacuum.

If you look along the firewall in the engine compartment, you will see a very small hose running along it with a tee in the middle. A hose from that tee goes through the firewall to the heater controls. Make sure there aren't any breaks in it. If so, cover the break with a hose of suitable diameter.

Next up is to check the vacuum pumps themselves. Drop the glove box all the way down and make sure that the levers coming off the pumps are still connected. Here's what I found on another '89:



Half of the split spigot on the door lever broke off and had separated from the pump lever. Looking at these pump levers while operating the controls with the engine running is another way to check if vacuum is present. Solution is to screw a small nut over the remains of the door lever with a glob of glue from a glue gun to hold it in place: