Looking for some trouble shooting help.
This is in my '79 240D
A/C was blowing ice cubes a couple of weeks ago. Since then , I installed a new voltage regulator - that is the only change.

I have no reason to think that there was any refrigerant leak - the system is dry everywhere, including the compressor.

I swapped the fuse. I checked the connection at the compressor (tight and has not moved). I shorted the pressure cut-off switch, still did not engage, and I replaced the cube relays with known working ones from my other 240D.

What do I do next?

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT