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Hi,
In 9 days we are getting a completely new HVAC and furnace system. So anything I do here only needs to work for 9 days...
My condenser fan motor keeps shutting off due to thermal overload. This of course happens in the heat of the day (6pm ISH).
UPDATE: THE SOLUTION IN THE VIDEO BELOW HAS WORKED! IT IS PRETTY CRAZY, BUT IT SEEMS TO BE GETTING US THROUGH. See the video for the experimental thermodynamic retrofit.
The motor is new as of last year, and we never had any problems last year. The first time it tripped I checked the run capacitor and it was 4.5 uF, rather than the 7.4uF called for by the motor. I replaced that run capacitor with one that reads spot on 7.5uF. It didn't trip again for a few weeks. These past few days it has been tripping every day. It has been hot (95F).
When this tripped today I cleaned the contacts on the contactor (they were somewhat dirty) with contact cleaner and paper strips. I also raised up the fan blades as high as they would go (went up about 1/2 to 3/4 inch higher than they were, not a huge change). They blades are still nowhere near the top of the condenser coils because the motor operates inverted and keeps them from going up any higher. The orignal motor and fan blades were similar in position.
It is possible that the fan blades are the wrong pitch for this speed motor. I think this motor is 1075RPM, and the original was 1075RPM. However, I had to replace the fan blades because we could not get the fan blades off the old motor (even borrowed a gear pullet from AutoZone... Tried a blowtorch... no luck).
So am trying to determine what my "fix" should be when this happens tomorrow. I could try to reduce the pitch of the fan blade to put less load on the motor. I am not sure how easy this would be to do well. If I don't get all three the exact same with the thing fly off and cause a problem?
Alternately I was thinking about buying about 8-16 pieces of copper pipe about the length of the motor's height. I would them use either zip ties (insulators, but small area) or metal hose clamps (with the screw) to affix these pipe around the outside of the motor in a vertical orientation (like hollow "roller bearing"). The idea would be that the pipes would act as a heat sink, and would take the heat out away from the motor, and also get the heat toward more where more air would flow over it.
I read someplace online that due to everyone else's AC motors and compressors running the power factor of the incoming power may be getting screwed up. Would increasing the run capacitor help? I have the old 4.5uF I could put it in parallel with the 7.5uF.
Any thoughts? The fix just needs to last nine days until the AC guys come to install the new system (they are booked up, like everybody else this season).
Thanks in advance. I know this isn't precisely electronics, but I might want to integrate an Arduino or Pic micro into the circuit to monitor things.. yeah!