I believe #5 is the evaporator temperature sensor in degrees celcius. 50 C = 122 F Since you AC is blowing cold, I know the evaporator is not at 50 C. Did you run this test after the AC ran for a least a few minutes? My 97 E320 #5 value levels out around 4 when I set the temp at 72 and the car has cooled down. Your core temps 3 and 4 also seem a little hi too. What was your temperature settings? One more thing, #7 should also drop when the car cool down. If the system gets a high reading from the evaporator, maybe the compressor is running hard trying to cool down.

I may be way off base, just taking from how my car behaves and all the reading I have done online.