Fan wiring with starter cap: One way full speed, other "low" speed. Can other way harm fan motor?

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,889
Have this fan from a MicroWave Oven (MWO). Wiring it according to the top schematic results in the fan running at full speed. When wired the other way (bottom setup) the fan still runs, but runs on a much slower speed. The question is: Can this harm the motor or the cap?
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MaxHeadRoom

Joined Jul 18, 2013
21,191
What is the reason for wiring the bottom method?
It will run the motor OK, just not very efficient.!
Compare the current between the two.
Max.
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,889
I've had the fan sitting on the shelf for some years. Had to figure out how to wire it. One way resulted in a weak flow, the other way a strong flow. I might want to use the lower method because I don't need the fan blowing like heck. But if I go with the lower schematic I wonder if I might hurt something. The motor or the starter cap possibly. So that's the reason for asking - to not damage equipment. The fan is currently sitting on the shelf awaiting connecting it up to something.
 

MaxHeadRoom

Joined Jul 18, 2013
21,191
The cap should be OK, probably Motor run rated.
As I said, measure the current, but it should be low enough not to damage cap or Fan.
Max.
 

MisterBill2

Joined Jan 23, 2018
6,685
In the lower circuit the capacitor is in series with the opposite windin, which may have a different resistance value and a different resistance. and it may not be able to handle the power without getting a bit too warm. So you might have a heat -problem, either in the motor or in the capacitor.
 
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