Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
From what you have described here and with the testing that was done and the common fault that causes this,this sounds like the blower resistor itself is at fault needing replaced.In some cases the blower itself can draw to many amps or short out/fail and cause the resistor to fail with both needing replaced.I can walk you through some more testing if you want so we can make sure these or which of these are the cause here just let me know if you would like to further test this.
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On the brown wire at the blower test this for a ground with your test light or multi meter connected to a battery power source.This wire should have fluctuating ground signal depending on the blower speed.The higher the speed the more ground it will have.If this is o.k. trace the red wire from the blower and see if there is a break in the wire leading to the resistor.If this is all o.k. let me know so we can continue as well as let me know the date of your vehicle looking at the drivers door sticker there should be a manufacture date on it that will help me look into the correct diagrams as theres two different options depending on the year and month this vehicle was built.
If you have power on the red wire at the blower and ground to the brown wire at the blower this indicates the blower motor itself is at fault needing replaced.The blower has the proper power and grounds but isnt coming on.In some cases you can confirm this with the heater switched on and engine running tap on the blower with a rubber hammer or similar.If the blower then runs then the blower needs replaced.If this is not where the voltage is and you are missing a power or ground to the blower let me know.
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