Author Topic: Condenser Fans running in opposite direction  (Read 1843 times)

Offline Sergroum

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Condenser Fans running in opposite direction
« on: July 30, 2018, 10:35:01 AM »
Hello, everyone.

Have you ever encountered a problem when fan motors begin to run the opposite direction without anyone rewiring anything?

This summer, I've had two cases now that are completely unrelated to each other. Where the customer swears that no one was on the rooftop, messing with their units. And I was there last year and I am damn sure the condenser fan was running properly. Except this summer, it began running the opposite way. Causing high pressure switch to trip and so on. I reversed the wires and it began running the right way. All other fans and compressors are working correctly, so it's not a matter of some electrician changing phases on the breaker for giggles.

If it happened once, I'd just think the client was confused. But it happened twice, with different clients.

Has anyone encountered anything similar?

Offline Jorgebaloy

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Re: Condenser Fans running in opposite direction
« Reply #1 on: July 30, 2018, 11:17:32 AM »
Normally condenser sucks air from the side and blow it out top so you might have it reversed before he oiled it if he didin't take off the wiring and rewire. A lot of motors has wiring that you just switch to make it run the other way. Hope this helps.

Offline Sergroum

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Re: Condenser Fans running in opposite direction
« Reply #2 on: July 30, 2018, 11:23:28 AM »
There is no oiling of these motors. And that's the thing. The client insists that nobody touched them after I was up there last year.

Offline walker

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Re: Condenser Fans running in opposite direction
« Reply #3 on: July 31, 2018, 06:17:20 AM »
A bad capacitor or bad winding in the motor can cause a PSC motor to run backwards.  Also sometimes they come from the factory miswired and they work fine for awhile and then start giving issues.

Offline Hvacpimp

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Re: Condenser Fans running in opposite direction
« Reply #4 on: July 31, 2018, 06:19:47 PM »
A bad capacitor or bad winding in the motor can cause a PSC motor to run backwards.  Also sometimes they come from the factory miswired and they work fine for awhile and then start giving issues.
Walker seems to have the answer on this one! I've encountered this before and that's what it was.

Offline Sergroum

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Re: Condenser Fans running in opposite direction
« Reply #5 on: August 01, 2018, 12:17:05 PM »
Thanks! I'll check for the capacitors next time.

I honestly dont understand how a capacitor would affect the direction of the spin, but I guess we'll see. It's definitely an issue that 'does' occasionally crop up.

Offline Admin

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Re: Condenser Fans running in opposite direction
« Reply #6 on: August 01, 2018, 12:30:23 PM »
A capacitor pushes the fan in the correct direction.  If the capacitor is bad, then anything like the wind, can cause the fan blades to spin, and the motor will run in whichever direction the blades are turning.

Offline DaveP

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Re: Condenser Fans running in opposite direction
« Reply #7 on: August 01, 2018, 01:17:48 PM »
happened to my own unit,  fan wouldn't always start, spin my hand in either direction turn unit on while fan in motion, away it went, wind would start it wrong way usually if i wasn't around, change the capacitor, back to normal

Offline Sergroum

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Re: Condenser Fans running in opposite direction
« Reply #8 on: August 01, 2018, 11:38:09 PM »
A capacitor pushes the fan in the correct direction.  If the capacitor is bad, then anything like the wind, can cause the fan blades to spin, and the motor will run in whichever direction the blades are turning.

Oh. Then the direction would be random. The capacitor isnt working wrong, it's just plain not working. Theeen probably not it. I've done a bunch of turn off/turn ons during diagnostics, and the fan would start up pretty reliably in the wrong direction. Switching wires around though have solved the problem, once again (I hope?) reliably. Though each time, I did end up changing capacitors as a preventative measure.

Offline Porcupinepuffer

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Re: Condenser Fans running in opposite direction
« Reply #9 on: August 04, 2018, 08:16:10 AM »
Is it single phase or 3 phase?

Offline walker

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Re: Condenser Fans running in opposite direction
« Reply #10 on: August 04, 2018, 08:59:20 AM »
Is it single phase or 3 phase?

Single phase. 3 phase don't use a capacitor.

Offline Porcupinepuffer

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Re: Condenser Fans running in opposite direction
« Reply #11 on: August 05, 2018, 06:58:57 AM »
Is it single phase or 3 phase?

Single phase. 3 phase don't use a capacitor.

Of course. When I read about switching wires around, I thought it could be 3 phase.

Offline Sergroum

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Re: Condenser Fans running in opposite direction
« Reply #12 on: August 05, 2018, 01:42:42 PM »
If you switch wires around on a standard 220v condenser fan of a residential unit, it too will start spinning the other way around. Doesnt have to be 3 phase.   Most condenser fans are 1 phase, even if the rooftop is 3 phase.