Whole House Fan is Running but too slow ?

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Old 10-04-20, 04:24 PM
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Whole House Fan is Running but too slow ?

How do you tell if it is the capacitor in this situation? The Fan is running but at such a slow speed it won't open the baffles... How do I tell if it is the capacitor on the motor?
model number,

whole unit.
 
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Old 10-04-20, 04:53 PM
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You need a meter to test the capacitor. The MFD rating should be listed on the capacitor.
 
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Old 10-04-20, 05:30 PM
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That's only an 1100 rpm motor. Very doubtful the cap is the problem.
If it is..... that motor should be hot.
Are you sure the belt isn't slipping ?
 
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Old 10-04-20, 08:08 PM
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when I pulled the belt by hand, it seemed to be tight enough. I have a multimeter. I haven't left it on to see if it gets hot because it wasn't pulling fast enough.
 
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Old 10-04-20, 09:43 PM
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Naive question perhaps, but what setting on the multi meter should I use? The video I watched said uF and since the poles are covered will it check accurately through the insulated wires?

 
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Old 10-04-20, 11:20 PM
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The meter gets put on UF and the capacitor has a rubber cover that needs to be removed to contact the two wires which will be on spade (commonly called fast-on or quick disconnects) terminals (there might be 4 of them but use the 2 where the motors wires connect) you will then put your meter probes on them since this is AC polarity does not matter. Also remember to do this with the breaker off so you don't get shocked or hurt.

Edit: From the motors nameplate this should be a 10UF/370VAC capacitor.
 
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Old 10-05-20, 05:42 AM
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The motor capacitor is for starting torque. An open or shorted cap would result in the motor not turning at all. You say the fan is turning slow so I assume the motor is at/near selected RPM. The schematic on the motor nameplate indicates 2 motor wires for speed selection. Did someone change the speed connection? The fan is belt driven. Does the motor and fan rotate easily with the belt removed? Do either /both require lubrication? When reattaching the belt, make sure the belt and pulleys are tight?
 
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Old 10-05-20, 08:43 AM
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Hi, the fan is operated by an on/off light switch. No one has changed the settings on the motor. When I pull on the fan belt the fan seems to move freely. I will try lubrication, but it seems that the motor is just spinning at that speed. I would be difficult to lubricate the motor's spindle as it is internal to the motor where the bearings are and it is face down.

Update: lubrication did not affect the performance....

UPDATE: Although we have lived in the home for 6 years, I did not know there was a secondary switch for speed. My son in law found it and we turned it to high, but it was still not generating enough draw to open the baffles on the cover.
 

Last edited by jefferis; 10-05-20 at 09:52 AM.
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Old 10-05-20, 11:16 AM
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Are the baffles able to be opened by hand and are they able to be moved freely? If so it's probably motor replacement time.
 
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Old 10-05-20, 12:04 PM
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Hi, Yes the baffles move by hand freely. The motor sounds pretty loud as well. Any suggestions on where to find a replacement. been looking online and HomeDepot has one for a 30" but not a 36" belt driven motor.
 
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Old 10-05-20, 12:27 PM
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No often thought of but the belt can be too tight. Been there Done that and the motor wouldn't even start, only grunt.
If remaining in that condition the motor will over heat very quickly.
 
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Old 10-05-20, 12:46 PM
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thanks, I removed the belt and flywheel and it didn't go any faster and still made too much noise.
 
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Old 10-05-20, 06:01 PM
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Belt drive fans are inherently noisier. We had many unhappy customers with hall mounted whole house fans. From the roar of the fan to the rattling louvers.

There are replacement two speed motors available but I would be very doubtful that will help.
What I have done is added a motorized unit to the dampers and then run the motor on slow speed.

I use the Dayton one from Grainger. It's in the link.
Motorized damper motor
 
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