Central A/C Compressor question

Old 06-29-13, 12:37 PM
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Central A/C Compressor question

The fan on my outside compressor unit stopped working. Compressor still ran for some time until the lack of cool air was noticed. Unit was turned off and A/C tech was called the next day. When the unit started, the fan turned on and spun, steadily slowing down. Tech said the fan was toast and he could replace it for ...get this....$900!!! or, of course...a new AC installation.

Granted it is an old 30 year-old GE system which probably came with the house, but I know enough to know that if it is only the fan, I can replace it for a lot less....so I did...for $150 (motor $100...[tech told me it was a "$500 motor"] and new fan blade with hub, along with a new capacitor for the $150 total)
R and R'd all the pieces being careful to correctly replace the wires in same place they were removed, and unit and fan started like a champ...cooling house.

THEN...within 3hrs the fan stopped again. Compressor still running, but no heat being drawn from the coils. Shut her down and suffered through the night.

Today, I disconnected the power to the new fan motor, took off the fan blades and put a temporary 110v shop fan on top of the unit and started the AC up... it is cooling now and will get us through this heat wave UNLESS whatever stopped the fan, also will stop the compressor or worse. The compressor is still running, seems a bit noisy, but I am gun-shy and super sensitive to this damn thing now...

***Will running the compressor, without the fan for a period of time, ruin the compressor?

***What else could be stopping the new fan now?

I should have restarted the AC this morning before I disconnected the new fan motor to see if it (new fan motor) started up as it should, but didn't...just went ahead and put on the temporary shop fan.

Any and all help will be appreciated. Not too concerned about having to fix (replace) it piece by piece...
Old 06-30-13, 05:10 AM
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What are the old motor specs and what are the new motor specs? Running the ac without the fan operating can and will damage the compressor over time (not instantly). At 30 years old your ac has had a long life and things are probably getting worn. I too would try replacing the fan motor first, but I would also start getting a plan together to replace the tired AC system.
Old 06-30-13, 02:24 PM
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replacing the fan motor can be a bit tricky 1/2 HP is not = to 1/2 HP in the fan industry, sounds crazy but its the industry. The best measure you can go by is to make sure its a TE(totally enclosed ) motor because of the elements, match HP rotation RPM and direction, Fan blade pitch, #of paddles and voltage and now te kicker AMPERAGE. Never use a motor with less amperage than the previous...if need be, go up a step in HP. Use a rain shield or slinger and new cap that matches the new motor. When installed amp the common leg of the motor. If its above the rated RLA on the data plate on the motor, it will fail. This sometimes happens because of the wrong pitch of the blade, or wrong RPM...you might need an 870 instead of a 1050... your comparing a generic motor to an OEM motor most likely is it the exact same GE motor? I think not! You likely got a Fasco or Baldor that was crossed if you still have the old one compare the RLA ratings if they don't match= or greater, return it for an improper match.
Old 06-30-13, 03:00 PM
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Did you remove the bottom drain plug from the new motor? Multi position motors usually come with plastic plugs in both the shaft & lead ends. If the motor is installed "shaft up" the lead end plug needs to be removed & vice-versa. Failure to do so can damage a new motor pretty quickly.

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