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Thread ID: 140476	2015-10-19 10:01:00	Electrial question - ceiling fan blowing not sucking	andrew93 (249)	PC World Chat

Post ID	Timestamp	Content	User
1410188	2015-10-19 10:01:00	I have a fan in the ceiling in the laundry that should be sucking air outside. However, it is currently blowing air into the laundry. It is ceiling mounted and cannot be flipped over. Can I reverse the positive and negative wires to make the fan run in reverse? Obviously I would need to isolate the circuit beforehand etc. but am curious to know if others have experience with this. Thanks!	andrew93 (249)
1410189	2015-10-19 10:20:00	Reversing connections will only work if it's a DC fan. AC motors don't work like that and of course there is no positive and negative in AC. If that just confused you don't touch the wiring! Sounds like it's installed wrong.	dugimodo (138)
1410190	2015-10-19 10:42:00	First question is: Has it worked properly before? If yes, then it's probably stuffed now, get it repaired by a qualified artificer. Otherwise.... some DC motors can be driven with reversed polarity just fine, but a lot will either do nothing or go up in smoke. Unless you know exactly what type of motor you're dealing with, leave it alone and get an electrician to look at it. Likely it's not DC anyway, and you've just got older wiring that's coloured red and black. Not to mention the fan blades are probably only designed for efficient airflow in one direction, so even if you successfully reversed the motor rotation it may prove fairly useless in terms of airflow anyway.	Agent_24 (57)
1410191	2015-10-19 17:41:00	Some Ceiling Fans have a directional switch on the side of the motor, but if it doesn’t have one you’ll need to speak to an electrician or you may jeopardise your insurance if you undertake wiring changes and have a fire.	B.M. (505)
1410192	2015-10-19 18:10:00	It is ceiling mounted and cannot be flipped over. Why does that mean it can't be turned? Can you not get at it, either from in the roof or by removing it first? If not, get a new one put in.	pctek (84)
1410193	2015-10-19 19:01:00	Reversing connections will only work if it's a DC fan. I think if it's a 3-phase AC motor reversing any two phases will make it turn the other way It is probably an induction motor (ie, no wired connection to the rotor). An induction motor works by mimicking 3-phase (sort of). It runs off 2-phases, the second phase being generated by a reactive device (inductor or capacitor) which gives a 90° phase shift. So you get 2 phases. That's almost the same as 3! I'm picking the capacitor is wired wrongly (though I must say my first thought is mechanical mounting like as pctek says)	BBCmicro (15761)
1410194	2015-10-19 22:23:00	It will be a shaded pole motor, reversing the wires will not change direction of rotation.	Terry Porritt (14)
1410195	2015-10-19 22:59:00	Have you cleaned the fan blade recently, taking it off to wash, then putting it back on "upside down"? You will not be able to electrically reverse the direction of the motor. As Terry said it will be a shaded pole motor made in millions. However a trick I have used in the past is to dismantle the little motor. The outside part is the Fields the inside bit that rotates has no wires on it. Take the Fields off, turn them upside down , put it back in & reassemble the motor & fan. Should the run the other way. Only if it is easily possible, don't force it. PJ	Poppa John (284)
1410196	2015-10-20 00:12:00	Unless the blade includes part of the motor turning it upside down will not reverse the airflow.	dugimodo (138)
1410197	2015-10-21 00:02:00	Here is a picture of the fan with the cover removed. The mounting is such that the entire fitting cannot be turned over. 6781 I believe it was sucking when it was first installed some years ago, but in all honesty I never checked it until now. There is no switch that I can see to reverse the direction of the fan.	andrew93 (249)
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