It has an issue with the heater system. The climate control seems to work just fine, and I get nice hot air or cold air depending on the setting (AC not working, just cold(er) ambient air).
It is only blowing air out the defrost and floor, it won't change and blow out the panel vents. I've seen references to the blend door, but I thought that was for hot/cold? I found a few threads about a vac actuator on the driver side of the heater box that may control floor/panel/defrost.


Which actuator controls the floor/panel/defrost settings?
Thanks!

This is all I could find right now, hope it helps.

Awesome, thanks much! That really helps.
I assume then, the #1 and #4 valves are vac controlled from the left side actuator? The vac line should come in on the right side near the programmer, correct? Looks like tonight I'll have to trace the vac lines.

First thing to do with this type of issue is check if the system is getting vacuum. The purple tube in under the passenger side dash can be checked. Or you can do it the other way. ....

Being an SSEi you are superchaged. Therefore if you look at the top of the supercharger by the throttle body there is a black plastic vacuum distribution piece. The brake booster in on the back fitting, the middle is the HVAC vacuum that is used to feed the diverters. Ensure that line is hooked up.

From there the line turns to plastic and goes into the wire loom. Remove the maxifuse center cover and look behind the passenger side strut. You will find that plastic tube emerge from the loom and become rubber to a check valve. Frequently this rubber has degraded. Confirm the check valve is in line so air can be pulled to the supercharger and not the other way.

On the other side of the check valve that line turns back to plastic and heads down to the frame rail. From the frame rail it goes up under the passenger front fender where it feeds the vacuum canister. After the canister the line follows back along the frame and into the cabin as the purple supply line.

I've seen the vacuum canister become broken, rubber hose degrade over time, check valve no longer working and a couple other issues. Typically though the issue is in the engine compartment.

Dan... maybe we can incorporate some of the above info into a fix up for 96-99 write up? 92-95 are similar but the vac canister is on the fire wall where the 96-99 cruise control module is located.

I've checked that it has vac to and through the line and check valve under the fuse cover, but thought it went straight into the cabin from there. The line after the check valve that feeds the canister did feel/look degraded, left nice black remnants on my fingers. I'll check both sides of the canister for vac. If all good there, I'll move to the plug under the dash.

Since you have it that far...it might be a quick one to move right under the dash to the purple line.

Ok, finally got a chance to get under the dash tonight. The purple 'hard' line goes way up into the dash area, so no way to check there without removing the entire vacuum plug.

I checked the vacuum bottle in front of the passenger wheel. There is an incoming vac line, with vacuum, but no outgoing line?? So I guess there is no real way to tell if it has a vac leak or not.
I found a hard line on the frame rail in front of the motor mount, goes back to a steel line, has a purple tag on it. Is this the line that terminates at the HVAC programmer? I traced it forward, and it goes under the radiator and comes up somewhere under the air filter housing.
So, I'm assuming the vac hose with the check valve under the relay cover terminates at the vacuum bottle?

Ok, more tracing.
After removing the airbox, I found the air tank under the ABS controller. The feed line was not connected. But, it also had no vacuum. I traced it to a small sensor/controller that sits right behind the alternator, and attaches to the alt bracket. It has vac in, vac out, and a 2-wire harness. I'm getting vac to it, but nothing out. The vac out has a short line connected to a small unit (the pass side of the 2) that sits just under the cross brace. From there it goes to the air tank under the ABS controller.

I'm going to temporarily connect from the vac source on the throttle body to the air tank and see if I get HVAC controls.

Anyone know what that part is behind the alt? Should it have vac passing through all the time?
Thanks!!

Looks like that is the evap solenoid for the vapor canister (air tank), so NVM.

Yep, that'* what it sounds like. There will be times that it'* on, and times when it'* off. When open you have a vacuum leak. So make sure it'* hooked up.