Attic Vent Fan - where to start troubleshooting

The wife and I have only lived in our house for about a year and I'm slowly fixing the small things that I find wrong. Our attic has a fan attached at one end with a small junction box with a knob to set the temp the fan comes on at, but as far as I can tell it doesn't work and never turns on. It did work when we had it inspected, so something changed/broke/stopped since then and I don't have a clue where to even start with trouble shooting. I'm ok with wood work and plumbing but I'm a raw novice when it comes to electricity, so any help or suggestions would be greatly appreciated.

 

Start at the breaker box, see if any breakers are tripped.
If one is hopefully flipping it back will make it work.
If not proceed up and see if the fan can move freely.
Moves then see if you have power to it with a meter.
Check it before the stat control and after it may be the controler.
Be carefull.

 

Check to see if there is a switch for the fan; ours was wired to a light switch in the attic. Even though the fan is on a thermostat switch chances are likel that there will be a standard on/off switch. Of course, check the breaker box. Last but not least, it could be the fan motor or bearing is out and the fan needs to be replaced. Most attic fans run about 10-15 years.

 

I looked high and low for a switch and didn't find one.

I did try spinning the fan and it definitely isn't "free", it spins but with a lot of resistance, like a friction drag on a fishing reel.

I have a multi-meter but am not really sure what I should do with it, I don't want to electrocute myself.

Fuse box is good, no tripped switches. I'm pretty sure the fan is from HomeDepot, seems like the former owner bought a lot of his house from there, and the reviews seem to agree that the fan isn't great and often dies after a few years, so I'm wondering if that might be it. I don't want to just go buy one ($100) without testing the current one first.

Thanks for the replies so far, ideas for testing the fan and instructions on what exactly to do with my multi-meter are greatly appreciated!

 

If the fan doesn't spin freely the bearings are probably piled up and that's your issue. What you can do is take it out and take it apart and grease/lube the bearings/bushings. Probably better off getting a new and better fan if that one is a POS though.

For any electrical work, if you're not real comfortable with it consider finding someone who is. Also I highly recommend those pencil type voltage testers. Like this:



The one like pictured will flash intermittently when it's on verifying the unit is working then they blink real rapidly and beep when voltage is present. You just need to hold it near or against a wire to see if it's hot before you go sticking your fingers in there.

 

I have the same issue. I have one of those attic fans that looks like a huge mushroom on the roof. Got some kind of thermostat on it and it don't work either. Way to hot up there to work on it right now, but it would probably help my A/C bill if I would just man up and get up there and fix it...lol

 

During hot weather, best time to work in the attic is early morning about 5AM when it has cooled down. Had several attic fans and they last 7 years here in NOVA where it is hot and humid in the good old summertime. Best to just get off the dime and buy a new one.

 

I'll second the recommendation of finding someone to help if you're not comfortable working on it yourself.

If you've checked the breakers and they're all on, I would work my way back from the fan's electrical connection and see if there's power at the fan motor. If not, then test in front of the thermostat. If you don't have power at the thermostat, then there's probably a switch somewhere that's not obvious so follow the wires to see if you can find it. If you have power at the thermostat but not at the fan, there's a problem with the thermostat and bypassing it should make the fan run.

Good luck.

 

sounds like the motor is bad. pick up a new motor and install. I've done this several times, not too difficult, just take your time and make sure the power is off. Hardest part is getting the motor back into the bracket centered correctly and fan blades back on. Good luck, you can do it.

 

Yup. Change that bad boy out. Been there done that. It's not too bad.

My experience was the same, we had a light switch in the closet where the heater was that controlled the fans. No sense running them in the winter.

 

Make sure there's not a light switch in the house somewhere that controls the fan. Mine was behind a door in a hallway downstairs and took a month for me to figure out what it was for...

 

The fan the OP is talking about is a gable vent fan (http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053)

Its mounted on 2 vertical studs that go right on either side of the gable vent. This fan is basically a large fan blade pressed onto a motor shaft. The fan has a thermostat with a dial like knob, and has settings for different temps (I have mine kick on at 100 F). From the thermostat box it had the usual White, Black, and Ground conductors.

I had to replace mine the month I moved into my house because it was shaking the whole wall. My fan was so out of balance, and for the price, it didnt pay to try and fix it.

Find out what that thermostat box connects to. It should go to some sort of junction box. Trace some other wires from that junction box and see if you can figure out where they go to. They may go to some switches that you dont know what they do (I still have 3 or 4 of them after 2.5 years of being in my house).

If you cant figure anything out, the next step is to see if the fan is getting power (as mentioned above). Find the junction box I mentioned earlier and take the cover off. With your Multi Meter (set the dial to 200 AC V) touch the negative lead (black) to the white (neutral) wires (you may have to remove a wire nut to get to the actual copper part of the wire), and touch the positive lead (usually red) to the black (hot) wire. At this point you should see something about 120 V. If you dont, you know this circuit isnt live. If you do see 120 V, go turn off this circuit breaker and reinstall the wire nuts).

You now know that the fan is bad and needs to be replaced. This is as simple as 4 screws into the studs and connecting the white to white, and black to black. PM me with any questions.

 

Hey gang, hoping for a little help. Attic fan stopped working because the belt was old and had come off. Motor worked. I just replaced the belt. now I turn it on and everything runs fine for about 10 seconds and then it shuts off. Any ideas?

 

You're probably running into a thermal overload situation where you actually have the motor exceeding its thermal rating due to either resistance of whatever the motor is running or bad insulation in your motor. I'd say remove the belt and see if the motor runs for more than 10 seconds as a starting point. Also, check to see if there is a bearing that needs grease at the fan.

 

Like some people have said start by looking for a switch, which you have done.
Second invest in a non-contact voltage checker as @fvtalon said, and make sure there is voltage at the thermostat.
Third, get an electrician (or someone who is comfortable working with electrical circuits) to swap out the thermostat for a switch when you remove power from the fan circuit to make sure the fan works.
4th if the switch turns on the fan once the power is back on then you need a new thermostat, otherwise you need a new fan.
Please follow all codes and safety precautions when working with electricity and DON'T work on live circuits! Good luck and be safe out there.

 

Make sure the new belt tension isn't too high. This would cause the motor to work harder and overheat, shutting down until it cools off.

 

I have one of those Home Depot gable vent fans and I wired a switch before the thermostat so I could shut it off when I wanted. I mounted the switch in the garage, next to the man door but near the top. Accessible, but not so accessible that it gets flipped accidentally.

The reviews for it are not good, if I recall mostly because there is no way to grease the bearings and they dry out over time then fail. I remember reading about someone adding a zerk fitting so he could grease it occasionally. Wish I had done that as mine has been making noise recently. I only run it occasionally now. It's in an exceptionally difficult spot so I've been putting off replacement until I have to.

The fan blades still spin freely on it though - I can see them rotate when the whole house fan is on and pushing air out of the attic. From your description I would second the opinion that the bearings are shot. It should spin easily without resistance.