Hi all,
I have been refered to the forum & i hope i get help.
I own a 300SE 90 model done 80000km.The a/c cools
for 10 min & then the compressor cuts off & does not
cut in again, restarting the car starts the a/c again,
for the time it works the cooling is perfect. I have changed
the following,

control unit
evaporator sensor
a/c relay
pressure switch

I would appreciate any help.

There's a sensor on the back of the a/c compressor that's designed to shut-off the compressor in the event of belt slippage/breakage.

Cycling the ignition reactivates the unit as you've experienced. There's been alot of talk about this here. Use the SEARCH facility. It could simply be that your belt is loose, or the belt tensioner has grown weak.