check you A/C compressor and compressor clutch. Maybe the compressor or clutch or both is acting up. Btw- How is the feeling of the Air coming out? does it feel really cold or warm but cool enough but not cool enough for a 100 deg day?

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2001 E55

2001 E320 Sedan

2001 Subaru Legacy

2006 SLK280

2016 Subaru Outback 3.6