Brother of The benz, stevebfl
Your right in asking if the recirculate door was open or closed; and I happy you found the joy in my remarks.
We all should be aware that 134A will not cool as well as 12.
In my old 1987 W124030 with 176,000 miles and with the exception of the manifold hose assy and one drier/reciever is still original and converted for the second season to R-134A.
Setting the temp control of the Automatic Climate Control A/C to 22 degrees C.(72 F) the cooling fan speed is reduced to maintain comfort on the hottest of days we have in Houston and frequently cycles the clutch off.
I don't know what the evaporator nozzle temperature drop is compared to the ambient temperature.
I do know that the return sample air satisfies the set temperature.
This brings to memory when Chryler Corp. converted The AirTemp Auto A/C units from R-22 to R-12.
The same complaints were voiced then yet we survived as we will overcome the not using R-12 in our older auto A/Cs today.
Happy Trails Beep Beep from The Spiderman in Houston!!!