Yep. I had looked up the codes. The E075 has been around for a long time, but I still get proper heat. That doesn't seem to be a problem, although I might look at replacing the aux pump sometime soon here.
The AC pressure sensor is my concern right now. Could it just be that my pressure is low. When I looked through the code list, I didn't see a code for low refrigerant pressure. If the pressure is low, it's an easy fix, where as opening the system is a much harder fix.
I also don't have much of the equipment mentioned in the WIS to test, so I was wondering about homebrew testing....

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'95 S320 LWB
'87 300SDL
'04 E500 wagon 4matic