Date registered: Aug 2009
Vehicle: '85 300D - 381K and increasing daily
Location: Youngstown, OH
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
i had the same problems on my 115. the dimmer wasn't to blame, but 9 times out of 10 they are so i'd start there. as for the blower motor, hopefully the motor itself isn't bad--those things are a bear on the 114/115. the whole dash has to come out. so for now, take your windshield wiper arms off and pop your hood, and remove the four (or six) pins that hold the cowl cover on. the center of the pins push through--you'll probably lose one or two of them but will be able to fish most of them out of the air inlet after it comes off. after pushing the pins through, the remaining portion of the fastener comes out (towards you), much like the glove box clips if you've ever had that out. once the cowl is off (careful--dont bend it) see if the fan spins. the bearings can be completely shot and the fan will still spin, mine's worked like that for quite a while. if the fan freewheels spinning by hand, folllow the wires to the plug on the firewall next to the heater selector valves, right above no 4 cylinder for a 240 or in my case no. 5. check all pins for voltage with the multimeter grounded to the battery with the defrost switch on I, II and III. also, check the blower resistor pack (big wirewound resistors under the cowl--cant miss it). i went through all this only to find that some kind of switch that shuts off the defrost blower when the AC blower comes on was stuck. it's by one of the control rods, under the dash, right above the fuel pedal. check this first since it's the easiest, and last, after everything else, since jiggling things under the cowl may solve half of the problem. let us know how it goes...there are a few other tricks to try. and pray to the god(s) of your choice that it's not the blower itself.
'83 300DT -- 284K (rust casualty-gone in 2009)
'76 W115 300D -- spun bearing at 400K+, RIP 10/31/12
'78 300CD -- 159K - sold or crushed by ex (cringe)
'83 240D -- 162K - totalled (not by me) (parts car)
'75 240D -- 91K - clean enough to eat off the frame
'85 500SEL Euro -- 196K - why not?
'85 300DT --
03/16/10 - 243K
05/30/14 - 381K (daily driver - it won't die!)