I have a 1986 190e that I've been working on. I've read almost all the posts and info regarding the numerous A/C issues with these cars. My situation:

1. Car only blows hot air. It will at times get cooler (slightly) but maybe that's due to the engine thermostat opening/closing?
2. A/C compressor only engages when the top of the three right side buttons is pushed (the defrost button?). Pushing the middle snowflake button does not kick in compressor.
3. I can hear the vacuum "thing" behind the glovebox actuate when the control panel buttons are pushed, but I'm not sure what it's doing. It does not seem to change the location of the air in the vent, although it does come out of the floor vents sometimes, but it's ALWAYS coming out of the windshiled vents, no matter what button is pressed (except of the off button).
4. Main issue is that it is ALWAYS blowing heat.

What I've done:

1. Replaced the heater valve under the hood. Didn't change a thing, although I would note that vacuum is never going to that valve to close it allowing cold air to get in (is that right?) no matter what the dash setting is.
2. Replaced the climate control panel with a used one that I was assured worked. No chage in problem.
3. Inspected fuses and none of the them appear to be broken and contacts look okay.

Next step? I'm really getting frustrated and don't know what the issue is or what to do. I know this has probably been covered before on this list, but I nee somoe help, please? TIA