a/c problems 1988 260 e

[hoss260e]

hello, i have 1988 260e with 115,000 miles and have had a/c problems since last summer. it's hot this time of year in charlotte and i am trying to get it fixed. a local mb mechanic put dye in system to check for leaks and identified a leak at the expansion valve. i ordered a new one online and he installed and charged the system with refrigerant, which he felt would solve my problem. now he says that an internal switch inside the compressor is cutting off which only allow the compressor to run for 10-15 seconds before shutting off. he says that a switch or relay used to be available to override the internal switch, but the supplier he used to be able to get it from no longer carries it. should i purchase a rebuilt compressor with or without clutch or is there such an override switch or relay available? i want to get the system working and cooling at it's maximum capability, but want to get it fixed in one shot, not by trial and error. prior to replacing the expansion valve, the freshly charged system would work fine and cool for a month or so and then would only blow warm or hot air. please help!

thanks, hoss260e