# Attic fan not running at top speed



## Irishslave (Jun 20, 2010)

I have an attic fan in a customers house that is used as sidewall vent. There is a handy box on the side where a switch or control of some kind once was. It is wired to a cord at present. There are two hot leads one red and one black. When I heat up either the red or the black the fan runs but not at full speed (the louvers do not open completely) when I heat up both the red and the black the fan runs real slow. I guessing there is some kind of control switch available since there is a external capacitor on this motor. Can anyone diagnose this? I think a rheostat type control would burn the motor up. AO Smith's website says the motor is a single phase 2 speed


----------



## GettingBy (Aug 19, 2010)

Check that the blade moves freely.
Check motor current draw and compare with specs. 

Then, after checking the capacitor for a short or an open, measure its value; for this you can use a 9 V battery, a DVM and a 1 megohm resistor from Radio Shack. I recommend checking the cap no matter how cheap a replacement cap is and no matter how close the parts store is.


----------



## ScipioAfricanus (Sep 13, 2008)

With two hots that means 240 Volt, maybe when you energized both you used power of the same phase?


Andy.


----------



## GettingBy (Aug 19, 2010)

I think the problem with the e-mail notification has been fixed! And the squeaky wheel gets the grease. . .


----------



## 480sparky (Feb 1, 2009)

ScipioAfricanus said:


> With two hots that means 240 Volt, maybe when you energized both you used power of the same phase?
> 
> 
> Andy.


The two hots means it's a two-speed fan.


----------



## Irishslave (Jun 20, 2010)

480sparky said:


> The two hots means it's a two-speed fan.


Thanks 480 I figured that from the nameplate on the motor. My next question would be what kind of control would I need? Would my local Electrical supply house be able to tell me as long as I have motor specs?


----------



## ScipioAfricanus (Sep 13, 2008)

480sparky said:


> The two hots means it's a two-speed fan.


Aha, thanks man.

Andy.


----------



## 480sparky (Feb 1, 2009)

I'd say a two-speed fan control.


----------



## Irishslave (Jun 20, 2010)

480sparky said:


> I'd say a two-speed fan control.


What would be the price tag by any chance? By the way funny joke about bin laden


----------



## 480sparky (Feb 1, 2009)

Irishslave said:


> What would be the price tag by any chance? By the way funny joke about bin laden


I'd say a twenty should do it.


----------



## Irishslave (Jun 20, 2010)

480sparky said:


> I'd say a twenty should do it.


Yeah and that's the one too because the customer said it was a rocker or toggle type switch. Hopefully when I replace it the fan will go full speed to open the louvers all the way. This is just one item on the handyman list. this is the same house where I melted my key on the light switch:laughing:If I think of it I will take a picture of the distribution panel, you'll like it. It has whites to the breakers, blacks to the neutral bar :clap: the panel is a stone cold mess too. I found wires laying right on top of the buss when running a new circuit. I've tried to talk them into a new panel but this requires license and permit. I hope I can get a good picture and get it posted


----------



## Irishslave (Jun 20, 2010)

480sparky said:


> I'd say a two-speed fan control.


yes sir you were correct, even on the price, before installing I cleaned the motor, fan blades, and enclosure w/compressed air as the drywall finisher used the fan while sanding and the motors windings were full of that wonderful white dust


----------

