intermittant vent. fan problems, W210
 

Occasionally, and it seems to be only the hotest days, the HVAC fan acts up. Sometimes the fan comes on as it should then slowly slows down to just a trickle of air or none at all, regardless of the switch setting. Sometimes it blows at about speed 1 when set at 5. Never blows harder than the setting though. Sometimes when turned off and left off a few minutes it will operate properly when turned back on. When doing its "trickle" stunt the air coming out is cold, so I know the AC is working, it just won't blow. I don't think it is a switch problem, I suspect blower motor (brushes) or relay (maybe). The cabin filters aren't plugged. What do you all think?