Central air condenser fan stopped working.

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  #1  
Old 08-07-18, 03:04 PM
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Central air condenser fan stopped working.

Have a 28 year old Amana ARCF48U01D condensor and it was fine when I left the house this morning but when I got home the fan isn't working although the compressor is. Turned it off and disconnected the blue #20 wire on the contactor and the black and brown wires on the front capacitor. Turned it back on to check voltage. Between ground and those 3 terminals it shows 120V. So I assume everything up to the fan is good and the fan motor is bad? Or should I have tested voltage with the fan connected?

Contactor:


Capacitor:
 
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Old 08-07-18, 03:24 PM
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The blue is the common, black is the run and the brown is the start wire.
Unless the blue wire connection was loose.... if the compressor was running..... you have power to the fan.

With the blue and black disconnected...... you should measure resistance across those two wires.
If there is no continuity.... the run winding is open or the thermal limiter has gone bad.
 
  #3  
Old 08-07-18, 03:59 PM
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Fan motor wires read:

blue-black 10.5 ohms
brown -black 42.9 ohms
brown-blue 32.6 ohms
 
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Old 08-07-18, 04:06 PM
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The windings are ok.

And the fan won't start even when you give it a push with a stick ?
 
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Old 08-07-18, 04:37 PM
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When I saw it wasn't turning I figured it was bad and removed it after finding those voltages. As for the motor test I was going by the suggestion that the first two resistance readings should add up to the third, which they don't. I can try changing the capacitor first.
 
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Old 08-07-18, 05:12 PM
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Put the fan back on and tried to get it spinning. Feels very stiff with the power on if I try to spin it.
 
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Old 08-07-18, 09:03 PM
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The cap is the first place to start.... although that one looks relatively new.
See if the motor shaft has excessive play either side to side or in and out.
The motor can bind if the bearings have too much wear.
 
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Old 08-08-18, 11:30 AM
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Well, I put in a new fan motor and run capacitor (the one in the front) and the fan works great but have to start it by hand. So I also replaced the start capacitor (not shown) and no change. The only thing left is the big capacitor in the back. I thought it was for the compressor but that works fine. The terminals are pretty corroded so I probably should replace it anyway?
 
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