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Tyndale 07-09-2011 05:30 PM

2 Pipe Fan Coil AC vertical Cab - 1/10HP Blower Motor High Speed Problem
"I have 2 vertical cabinet AC units in my condo, 300 & 800 cfm, each having a 1/10 HP 115V 1050 Rpm, 3.3 amps with 5 speeds but the actual units switches only have 3 speeds.

The motors have gone bad over the past 15 yrs and I have recently bought and tried to install 3 similar motors with different but as close to the amps per HP/speed as the original motors and the same thing is happening with all 3 new motors. *The High Speed setting runs for approximately 15 minutes before it starts to smell like it is overheating and then the motor shuts down? *

The condo is 120v normal household wiring. I actually have purchased 3 diff motors. *Current one is the closest match I could find to my original motor which is: *5 inch diameter, High Speed1/10 HP @ 3.3amps, Med Speed @1.1 amps w/ 1/35th HP, Low speed @ .76 amps 1/70th HP, *115V, 1050 RPM, 5 Speed (but only use high,
med & low), Dbl Shaft 10" x 1/2", Shaded Pole, 60 HZ, Auto Overload, sleeve bearings.

2 of the motors are 1/10 HP but I could not match exact amps at high, med & low settings so the 1st one had 3.2 amps @ 1/10 HP & the other is 3.6 amps @ 1/10 HP. *3rd motor I tried was a 1/6 th HP @ 8.6 amps. *All 3 would only run for approx 15 min on high and then smelled like the motor/wires were overheating or burning and the would automatically shut down. I could wait 1/2 Hr & turn back on but after 10 min they would do the same thing & shut down? *I have been able to keep the 1/6 HP working on med for the last week without shutting down, but it does not cool my living room down enough w/90 degree + summer. *I also have been able to keep the 1/10th HP motor in my Bdr running at Med, but it shuts down on high after 10 min and smells like it's overheating?

Can you tell me is this because the new motors do not exactly match the old motor amperage at various speeds or would this be due to a bad wire from the speed knob the motor or a problem with my condo wires to the speed knob. I can't believe I am having the same problem with all new motors (AO Smith & Packard Ind) and in both rooms? *

Any help or pointers would be greatly appreciated. Tyndale"

beenthere 07-09-2011 08:14 PM

Was the old motor a PSC motor, or a shaded pole motor. Shaded pole motors don't use a capacitor.

Tyndale 07-10-2011 12:17 AM

The old motors were also both shaded poles. A master electrician @ Home Depot told me he thought the problem was the Thermostat had a bad capacitor and that is why the high speed does not work properly (probably getting too much current on HS but OK on Med & Low)

Could it be that I need a new Thermostat and if so, where do I buy one for a 3 speed fan coil unit, since I only get AC when the Bldg mgr turns on the Chiller unit and then heat when he turns on the Boiler ?

beenthere 07-10-2011 04:06 AM

If the new motors are PSC motors. You need to use a lower horse power motor. When replacing a shaded pole m otor with a PSC motor, the PSC motor must be a lower HP then the shaded pole was, or it will burn out due to not enough load on it.

The thermostat should not have a capacitor in it for the motor.

See if you can find a lower HP motor, 1/15.

Tyndale 07-10-2011 09:20 AM

Thanks for asking, but the old motors and new motors are all shaded pole motors.

beenthere 07-10-2011 12:50 PM

Check the voltage while the motor is running.

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