Mercedes Benz repair: 1987 300E A/C Problem, mercedes dealer, condition thanks

Question
Hello.  I have had this 300E for over 4 years now.  Since I have had it, the A/C has never workded properly.  When the push button is engaged, the compressor comes on for a few seconds, then shuts off. It will not stay engaged.  If the car is shut off and a/c is engaged again, it does the same thing.  I have changed the speed sensor on the compressor, the a/c relay, the freon, and have even tried different a/c in-dash units and still the same problem.  Others have tried to fix it and they wired it to check out the compressor and with them hot-wiring it, it rain ice cold, but they could not fix it to work in normal condition.

Thanks much

Answer
Best guess:
One or more of these parts is bad...

A/C ACC Temp Sensor...
A/C Compressor...
A/C E.T.R. Switch
A/C Pressure Switch
A/C Relay
A/C Temp. Switch
Sampler Blower Motor

Yes; the compressor can still be bad, if it has too much rotation resistance = speed sensor shuts down the system before it breaks the belt and leaves you walking.

Have you taken it to a Mercedes dealer?