Originally Posted by jcyuhn

Have you made the modification for 100% recirculated air? A standard 123 mixes in 20% outside air even when in recirculate mode. Given the humidity in DFW lately (temp: low 90s, dew point: 72) your discharge temps will be quite adversely impacted by all the moisture which must be condensed out of this air.

I found the a/c in my '84 300D inadequate around town and marginal on the highway in Dallas. Modifying the fresh air door to close when in recirculate mode was good for a ~5 degree drop at the vents on a hot, humid summer day. Somewhere way back in the archives (or on the old Mercedes mailing list run out of Austin - anyone remember that?) is a write up of the process.