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bbphillips

Whole house fan

22 posts in this topic

Was running the whole house fan for the first or second time this season and it just up and quit. It's a pull switch on/hi/lo settings. I thought my wife had turned it off so I pulled the chain a few times to try to get it back on. Point being I don't know if it's on or hi or lo right now so I will definately be de-energizing it before working on it. No breaker is broken.

Upon inspection I see that it has a big capacitor (start up cap?)and then an unknown component that is a black rectangular thingamabob that is about 1 inch by 1/4 by 1/4 inch. It has two spade lug connectors attached. No obvious circuit breaker or reset button.

Obviously I haven't gotten too far into this so I'm looking for basic direction. It's only mid April and it's already too hot to be in the attic for very long.

My question is, does anyone have a generic schematic of a whole house fan? I want to identify the unknown component and determine if the capacitor could have gone while the unit was already running.

Thanks!!

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Need appliance parts? Call 877-803-7957 now!

Is your capacitor? oval or round?

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round

about 1 1/2 inches by 4

#97F4525

16?f 307vAC

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Probably a start cap. Does your motor try to start? Hum? Or anything?

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No, the motor does not do anything, no humming or buzzing. It is not frozen, it moves freely when I rotate it by hand.

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if the capacitor is rated at 16 mfd and 370 vac,it is a run capacitor,but the motor will be a p.s.c. type,meaning it requires that capacitor for starting and running to cause phasing in the windings,best thing is to remove the cap and check it for continuity with your ohmeter,should show quite high resistance and gradually climb as you watch it,then reverse the leads and it should gradually climb down-if it does this,it is probably ok,if it shows on open circuit,or very little resistance and does not change,it is pooched.

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Thanks for the direction. So the cap could have failed while the fan was running and this would have stopped it?

I'm not going to be able to get to it for a little while, I'm at work:D. I don't like things that can bite me even when power has been removed and I know that caps can do this. :yikes: I'll just have to work slowly and keep the kids away from me while I work. They love to say "boo" right as I touch something just so they can see me jump LOL.

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If it doesn't try to do anything I'd check to see if I had any voltage to the motor.

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Thanks,

This is why I was looking for a generic schematic, so that I would know where to find what voltages. I know it's probably not tough for most of you but I don't have a good enough general knowledge to be able to just see how this is set up.

Thanks again.

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The motor should have a voltage rating on it somewhere. Also, be aware that some motors can be dual voltage depending on how it is wired.

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OK, I'm just getting back to this. Thankful that the weather has been cooler!

Reading the cap I get 43ohms either way and it does not drop or go up, even after reading for 20 seconds.

I have tried to attach a picture. I want to know what the black, rectangular thing is to the right of the cap. It has two spade lugs. It reads a straight short either way, no resistance.

The landord sent a "repair man" to look at it and since it was something harder than just the switch or a breaker he said "dunno". Thanks bud.

Appreciate any help,

Thanks,

Bruce

post-2815-129045090733_thumb.jpg

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you need to first remove the wires from the cap to read it,at 43 ohms,you are reading the motor winding- the other device appears to be some sort of thermal sensor or fuse,and since it measures closed,you can assume that it is o.k.

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Thanks, I should have remembered that!

I'll have to get back to this later this avo. Got to get out and get some errands done.

Bruce

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bb, your schematic is right on the side of your motor.115v and ccw rotation. Can't make out much else tho. Check for voltage if it doesn't do anything.

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OK, I'm back at it.

Yes, the schematic I was looking for was right there on the motor.  Thanks!

Disconnected the cap and found that it was open. So there's the problem. Now to get a new cap!

"97F4525

15uf

370VAC 60HZ

Protected P965

P10000AF(or P)C"

Where would the best place be in your experience? Does Repairclinic.com carry these? I tried but I couldn't find whole house fans as a category to start my search.

Thanks!!!

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take the cap with you and head to a heating supplier and match one up,the keys are the microfarad rating (15uf) and the rated voltage (370vac)- if you can find one similar in physical size,it makes installation that much simpler- be sure to connect the new one exactly the same-one of the terminals will be marked on the cap- this signifies the plate within the cap that is closest to ground.

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OK, got the new cap but I don't see where the terminals are marked in any fashion. Nothing apparent on the old or new cap.

Is the position of the label on the cap the key (ie. the label is always on the + side)?

Thanks!

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just hook up the wires on the new cap as pictured in your photo and you should be good to go the old model caps had marking, but these later model caps do not and it shouldnt really matter, I dont think it woukld hurt to hook it up one way or the other

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Well I hooked up the new cap and still nothing. I checked the new cap for continuity and it read open also. Called the place where I had bought the new cap and they said my digital multimeter is probably not big enough/good enough to charge/read this big cap. Bottom line is they said it probably isn't the cap.

Checked resistance through the motor and found that the only lines I get resistance on are the white/brown (43ohms). See attached picture. Between white/red or white/black it's open. Between brown/red or brown/black it's open. Bad motor?

The motor does say it's thermally protected. I would think that would mean that if it overheated it would turn off until it cools down and would kick back on.

One other thing: where the fan plugs in the outlet has an open ground. I would think this would be more of a safety concern and the open ground would not prevent it from running. True?

Thanks for putting up with me.

post-2815-129045091002_thumb.jpg

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bb, sounds like a bad motor, but I'd still check for voltage before I chucked it.

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white is common on that motor black is high and red is low if you have nothing between black and white or red and white then you have a bad motor.

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  You mentioned that you had an open ground. Not the ideal situation. If the motor was grounded, it should trip the breaker / blow the fuse, but with no ground wire to do this, it wont happen. Check for ground by isolating the incoming power leads, ( shut off breaker first pls ), and checking each wire  to ground by using multi -  meter, set to ohms ( put one  lead on the casing of the motor, making sure you have good contact with the frame ) . Ideally reading should be infinity, or it may say O/L ( overload ) on the meter. (  Normally you would use a " megger " to test the winding, and put a higher voltage on than the motor normally runs. However, since Im assuming you dont have one, you can use a meter ). This only puts in the 9v battery power, but it may show up. If its grounded, its shot.

Note: the windings may be good, but if you have an ohm reading to the case of the motor, the motor is toast.              Pls get that ground wire fixed.

(In canada, if the wire does not have a ground wire, (older wiring ) you can install a Ground Fault receptacle, as an option. Might be the same in US. )

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