Swamp Cooler Problem (periodic shutoff)

I live in Colorado, and am having problems with my evaporative cooler. After running for about an hour or so, the fan always shuts off, even though the water pump continues to run. This applies for all settings (high cool, low cool, high vent, low vent). After resting for an hour or more it will work as normal.
The fact that the water pump is still running seems to tell me that the problem is not electrical. Any ideas? is this normal for swamp coolers?
Any help is much appreciated!
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My garage cooler does that once and a while. It has electronic controls with a remote control. I just unplug it for a while and it seems to reset.
AZCRAIG
www.vintagetrailersforsale.com

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snipped-for-privacy@gmail.com wrote:

The motor probably gets too hot and the thermal cutoff opens. When it cools sufficiently the cutoff snaps shut and the motor starts.
You have a problem. When was the last maintenance done and how old is the motor? most likely the fan bearings or the motor bearings are going. Fan bearings are cheap and can be easily replaced if you are a do-it-yourselfer. If the motor bearings are bad, the easiest and likely the cheapest solution is to just buy another motor.
You can tell if the bearings are bad if after you loosen the motor and remove the fan belt you can move the motor shaft any perceptible amount at a right angle to the motor shaft. Same with the fan shaft.
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Thanks so much for the help guys! Before the next heat wave I'll crack that baby open and see what's going on.
George E. Cawthon wrote:

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snipped-for-privacy@gmail.com wrote:

Most coolers have an adjustable pulley on the motor shaft. A good installer is supposed to set the pulley diameter adjustment so the motor runs at it's rated current. It sounds like your motor is overloaded and that is tripping the built-in thermal cutoff. Have somebody who knows what they're doing go up there and adjust the pulley for the proper loading.
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Tim Killian wrote:

Yes the motor is overloaded, that's why it gets hot and shuts off. But if it has been working ok before, it has nothing to do with the pulley.
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George E. Cawthon wrote:

I live in New Mexico and have a similar problem. Just this season, when the fan is on "high" (I only have 2 settings), it will all of the sudden slow down to low (for 5-30 seconds) and then speed back up again to high. This has never happened before and I have lived in the house for 3 summers. I do the maintenance myself, but I didn't notice anything untoward when I was setting up the cooler this spring. It sounds like it might be the motor and/or bearings? But how do I find out? And is it easy to replace the motor? Thanks!!
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The most common reason for the motor to periodocly shut off like this is that it is over heating and the thermol protection system kicks in to protect the motor.
The most common cause for a motor to over heat; is the belt is simply to tight. You could have worn pillow bushings, but if they are causing that much pull on the motor you would hear a god awful noise from them.
To test your belt tension grasp the belt between your thumb and forefinger and apply light up & down pressure (approximatly 3 lbs). The belt should only move about 3/4 to 1 inch.
To adjust the belt varies, usually you will find a bolt that holds the motor mounting bracket. It is usually in a cresent shaped slot. Loosen this bolt "a little" and move the motor toward the pulley slightly. If you move it too much, just redo it until you can only move the belt as above. If the belt is too loose, the worse that can happen is the belt might slip a little.
To learn more service and repair information on evaporative coolers, visit: www.easycoolercare.com
Larry Galpin The Cooler Doctor
Service, Repair & Enhance the Performance of Your Cooler Yourself and Save $100s Every Year!
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