is it hot or ambient? likely is a defective duo-valve, there are two vaves hence the duo part, the best way to test them is turn the temp to low, and then hit the EC button to turn off the a/c compressor. if the temp is still hot you will need to verify the duo vave for that side is getting the signal to close (they are open by default, power closes them)
if the air you feel is ambient and not heated, you may have a low freon condition or a partially clogged receiver dryer

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1967 250 S
1967 280SE
1968 250S
1971 280 SE
1973 220
1974 280 S
1975 450 SEL
1976 220 D
1979 300SD
1983 300 SD
1985 230 TE euro
1986 280SL
1986 500 SEL euro
1986 190E 2.3
1990 300 SE
2003 C230 K
2004 C230 K
1987 560SEL
1987 300SDL now in canada
2005 C230
1998 C43 AMG Sold to DON
1993 190E 2.6
300TD Former daily driver Totaled
current:
R320 CDI
Ram 2500 Cummins