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I installed a new fan motor on my Trane condenser. It's 240V three-wire Genteq motor that's described as clockwise shaft-up rotation

https://www.northamericahvac.com/trane-american-standard-condenser-fan-motor-1-8-hp-230v-mot18688/.

Wiring diagram on the fan shows purple and brown connected to a 30/5uf capacitor and black as line (L2). Fan resistance - purple to black is 40 ohms and brown to black is 60 ohms indicating that the brown is start and purple is run. Capacitor is known to be good and wired with fan brown lead to FAN and fan purple lead to HERM. Capacitor common is L1.

Black fan wire is connected to black side of the contactor - L2. In this configuration the fan runs counter-clockwise shaft-up. When polarity is reversed and improper to the fan wiring diagram, fan runs clockwise shaft-up.

I'm out of ideas on what can be wrong.

Sorry for the poor quality pics.

image image image image image

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  • Does your fan motor have a rotation direction arrow on the sticker? If so, does the arrow agree with CW shaft up? Is the motor rotating in the direction of the arrow or opposite to the direction of the arrow?
    – Jim Stewart
    Jun 5, 2021 at 18:49

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The herm terminal on the capacitor is for the (hermetically sealed) compressor. The condenser fan motor should be hooked up to the common (labeled C or COM) terminal and the FAN terminal. The third fan motor wire goes wherever the wiring diagram says it should go. You should have a wiring diagram, with the colors for each wire plainly marked. My wiring diagram is in the Installation Instructions booklet left by the crew that installed the unit. You mention the wiring diagram on the fan motor. You shouldn't use it, because it doesn't include the compressor wiring. The dual capacitor starts/runs both the compressor and the condenser fan motor. The compressor should have one wire hooked up to COM and one wire hooked up to HERM on the dual capacitor. The third compressor wire goes wherever your wiring diagram shows it should go. The fan purple lead going to HERM is clearly wrong and should probably go to COM on the capacitor. I had my dual capacitor replaced by an HVAC tech who wired the fan to HERM. This caused my fan to run hot until thermal protection shut down the motor. The motor temp. was 235° at that time.

If you properly wire the capacitor and the motor runs backward let me know.

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  • Since my post, I’ve had two AC techs look at it. We’ve concluded that the fan and motor were replaced with ccw rotation. Probably should buy paired motor and blades in the future. BTW if you flip the blade over, it’s doesn’t change the airflow. I had physically do it to convince myself.
    – Clifford Eby
    Jun 5, 2021 at 18:52

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