I've solved cooling issues on my grandads E220 (W124) my kid bro's 190e (W201) and my 190e.
Just for reference, the ambient temp where we are is like 30 deg celcius and all of our cars' running temp are around 82 to 85 deg in stop-go traffic.Never had a report of even reaching 100 deg!!!
My kid brother recently drove to Malaysia for the F1 races and he was stuck in a 1 1/2 hour jam coming back from the races and he reported that his running temp was at 85 deg all the way!!!
Back to your problem...
1 Fan bearings are going south???Source a cheap replacement from the wreckers...
2 I normally test the relays by applying 12V to it and use a multimeter to check the contacts.
From experience, if you are running around 100+ in low ambient temperatures, the electromagnetic clutch fan is not working (the big engine fan).
If it's working (it's electromagnetically locked to the engine somewhere above 100 deg celcius - i forgot the actual value), it will spin with the engine speed.If you are running at above 100 deg, you can rev the engine and get a friend to see if the clutch fan spins faster when you rev.If it consistently spins at the same velocity regardless of engine speed, it's not working.
3 possibilities - Fuse (unlikely), clutch fan temp sensor or electromagnetic clutch.
Of the 3 cars, only mine has 2 aux fans (driver and pass side).And yes, one spins faster than the other. One works off a temp sensor and the other works off both the sensor and the aircon high pressure switch.
Check and let me know if u are unsure. I can post photos if u need 'em.
Babybenz 1991 190e 1.8