1995 S500

Climate control has been going "belly up" intermittently for a while now. When it goes "nuts" the display will freeze or go blank, and the blower will run on HI and at full HOT thru the vents. It will occasionally begin working properly again, as if nothing was ever wrong. Other times, it remains "nuts" for several days.

I was able to determine that removing a fuse under the hood would make the blower shut off, unless the headlights were turned on, in which case the fan will run on HI whenever the headlights are on.

I was unable to try to get the unit into diagnostic mode cause when it is "nuts" the display and buttons are nonresponsive.

Today when I started the car, the unit was functioning normally. I went into diag mode and it was FULL of error codes, both E0 codes and E1 codes. Probably around 60 or more error codes had to be cleared out. When I finished, I noticed that E0 13 would keep coming back, even after being repeatedly cleared over and over. My chart must be wrong, cause it says that E0 13 is a rear control error (and I have no rear control). Anyhow, the unit worked good today until I went out for lunch and it was "nuts" again.

I am suspecting that the "head unit" may be the cause so I beat the crap out of the side of the center pod with the palm of my hand, and the system began working properly again.

So here's the questions:

#1) how likely is it that I have an intermittent connection to the head unit? Or is it more probably that something INSIDE the head unit is amiss?
#2) If I take it out to send it to ProgRama for repairs, I'd like to know the tricks to getting the dash apart. I know how to disassemble a 126 dash, but not a 140. Does somebody have the disassembly procedure?

I called ProgRama to see if they had a unit I could swap out for my bad unit and send them mine as a core, but they said they did not. They said they would need to actually repair mine rather than swap one out. This means the car will remain disassembled for pretty much an entire week. No biggie - I haven't driven it but once since Thanksgiving cause it was "nuts" and it will broil you out in a hurry...

So who knows how to get the climate control unit out of a '95 W140?

thanks