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Q: The blower motor just stopped working. on 1998 Mercedes-Benz S420

I just picked up the vehicle at body shop having the front bumper repaired. Turning on the air conditioner, no air flow is generated. I tried to remove "auto" set on driver side but this stays activated ( at least light is on). When I try override and setting fan to high directly, nothing. Defrost/heat/air all result in same result. Fuse/resister/switch gone bad or is the blower the issue? The sensor in the front bumber the issue? Any assistance is appreciated.
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Hot day, long trip, aircon on; started smell like something electrical burning. After an hour, the fan stopped.
I removed the fan; simple to do; takes about 10 minutes. Observed the motor commutator was damaged. Bought a new motor (not including whole assembly with the fan cage) online for about $140. The whole assembly at Mercedes dealer is over $1200; online prices are several hundred.

The problem is that the fan cage is a plastic part and needs to very carefully removed off the motor shaft; try spraying with liquid wrench, support the fan with some wooden boards and tap down on the motor shaft until it releases. Upon reassembly, the fan cage must be in balance with the motor or else you'll get vibrations at different motor speeds (as unfortunately I did). It took me about 2 hours to reassemble, test for vibration, take blower out of its airbox, visually observe out of balance of the fan cage, heat to soften the fan cage near its spindle and bend it in order to make it straight and balance. I finally achieved balance to perfection with no out-of-balance vibration noise, got it re-installed. It works like new for $140.

It would only be about a 30 minute job if you buy the whole blower assembly with the fan cage; see
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The sensor in the front of the car is for outside air temperature it shouldn't stop the blower motor from working.I am not very knowledgeable in Mercedes but if you need test procedures wiring diagrams ect...... There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate
Thanks for the response. SInce I wrote, it has worked on/off intermittantly. It seems to be the blower motor i guess. The link will be helpful to get the manual. Any idea where the blower motor is located on the car anway..hopefully a job not to difficult?
Have a 99 S420, had the same issue. Bought a blower relay off of e-bay, one of the wires was loose causing the problem. replaced it and have had a blower ever since. the blower is on the passenger side close to the windshiend. Remove the screws on the plastic panel running from the right side across under the wiper arms, this will allow you to access the blower motor and relay. Two screws and three connections and your done.
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