E320 2001 Climate Control

I would start off with the climate system air filter... have you ever change it?

The car, I believe, has the original filter. I will give it a look.

Sounds to me like the failure of the blower regulator, a very common issue on these cars.

If you search for some MB forums, you would even find DIY guidance to fix the issue. Some basic knowledge and experience needed. Could also be the blower motor but the regulator is the more likely issue.

I took the air plenum apart last night and the squeek is comming from the fan. The fan spins freely and is not rubbing anything. It also appears the only thing acting up is the fan speed. I followed a guide on the internet and found an error code of Eb FF in the climate control. I suspect the idea of a bad regulator is correct.

The interior courtesy lights of our 1988 E300 only work sporadically when the driver's door opens. We have had the car repaired, but the problem remains. Any ideas?

I am unable to syncronize the right front headlight Wiper to rest in the down position. Is there a separate motor for the right and left washer/ wipers. How complex are these to change?

Thanks to all for the advice. It turned out to be the blower regulator. The symptoms included: surging air volume, manually all speeds of the fan worked, worked perfectly part of the time, squeak from the fan when the surge would turn air volume very low.