AC compressor clutch disengages after 10 minutes
 

The air conditioning on my 1987 300TDT works great -- very cold -- for about 10 minutes after I start my car. Then the clutch on the A/C compressor disengages, causing the air to lose its cool. I have a 2 year old remanufactured compressor, and the AC (red) switch, expansion valve and dryer were replaced. I just recharged the system with a can of 134a (conversion was done by previous owner).

Any idea why the AC compressor clutch stops engaging after 10 minutes? It seems to happen when it's more than 85 degrees outside. Thanks