I hope I don't sound rude in asking this, I certainly don't want to sound that way. What exactly are the symptoms? You're all over the place in describing what's going on.

I remember in a college Physics class there was this guy who would have scribbles all over his paper and try to ask questions of the professor in a very unorganized manner. He had all the information but it was scattered everywhere.

What exactly is the problem? Is your problem that you have 45 to 50 degree air with 75 degree ambient?

Are you getting condensation drain water out the bottom when the a/c is running? If so, then the refrigeration portion is probably okay, and I THINK that's why you're describing all these other things.

If your refrigeration is okay and the heater valve is not allowing LOTS of hot water, then you are probably getting fresh air instead of recirculated air. Go to that series of vacuum lines just behind the glove box and remove the top two one at a time and apply no more than 4 inches of vacuum and see if it will hold vacuum. If one or both will not hold vacuum, the problem is your fresh air/recirc pods in front of the HVAC box at the top center of the dash.

I have my 300E apart as we speak replacing them. This is a HUGE project. The entire instrument panel must come off to replace them.

But, DON'T jump to any conclusions until you've done some analysis. If the sampler blower is turning when the ignition is on, I would forget about it for the moment until you check the pods. If the heater valve or the control of the heater valve were bad I think you would be absolutely frying, so my gut says that's not your problem.

Check the pods and get back to us.

Best of luck,