Probably a restricted expansion valve. The only way to know for sure is hook gauges up to the system and monitor the pressures. That will tell you if its a freon issue or an expansion valve issue.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.