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Old 04-10-2021, 11:32 PM   #4
vishmutzy
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Join Date: Nov 2014
Location: SE Michigan
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Good advice on cleaning & greasing everything. I did an in-door clean & lube on both front doors and noticed improvement in the closing operation, but I suppose next time I have the doors apart I'll remove the regulator & glass runs to properly inspect & clean everything.

However, the current peaks that overload the fuse occur after the glass stops moving and the motor stalls (zero rpm = highest torque & current draw for electric motors). So regardless of the condition of the regulator & glass sliding mechanisms, the fuse is being overloaded once the motor(s) stalls at full closed position. Might be that the 30 year old motors have shorted windings that are causing high current, maybe corroded switch contacts are causing higher resistance.

Furthermore, the driver door motor had the highest stall current at 15A, the passenger door was second at 13A, and both rear doors measured around 10.5A. So that rules out a single "bad" motor, meaning that the design of this circuit simply doesn't allow raising more than one window at a time without exceeding the fuse rating.

We know that fuses are designed to sustain over 100% of their rated current capacity; that maximum point of failure will occur suddenly with a high load or gradually with several lesser loads. So I will probably be able to raise both front windows several dozen times before the fuse blows, or both rear windows several hundred times, or three windows maybe once or twice.

Last edited by vishmutzy; 04-10-2021 at 11:55 PM..
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