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bubster020 · Sep 2, 2007, 05:28 PM

I just replaced the blower motor because the a/c guy said it was bad and was going to charge me $420 to fix it so id id it myself. I got another motor, the old one was 4 spd 960 rpms, and the new one is 3 spd with 1075 rpms, the people said it was okay to do it like that and got a new capacitor as well. I hooked all the wires right, it had worked for a week. Then yesterday the a/c came on and the blower motor ran for approximately 1 minute and shut off. I checked the temp and it didn't get down to the temp I wanted. The units stayed on but the motor just stopped. I shut everything off and turned it back on and the motor started running again then turned back off. I am exhausted on working on this thing and need some help of what it may be. I am thinking relay. The breakers never tripped or anything. If someone could please HELP ME ITS HOTT!?

acetc · Sep 2, 2007, 06:19 PM

One thing you might look at is the wiring correct? Some motors will wire differently, especially the capacitor may not get any other wires then the two brown wires if it has two brown wires, some only have one. The capacitor is something you might look at also, they do fail quite often. You may want to check voltage at the motor when it fails, you may have a bad relay. Good luck. Mike

letmetellu · Sep 2, 2007, 07:06 PM

Just a note about the price you were going to be charged, I think that the quote might have been a little high but I don't know all of the details, it could have been an extremely hard job to do. But you can see that is is not always easy to repair or replace motors and if he had all the trouble that you are having he probably would have lost money on the job.

You don't say but I am assuming that the motor you changed was the condensing fan motor on the outside unit. So I will go from there. After the motor runs for the short time that you described is the body of the motor extremely hot? That could mean that the motor does not have enough horse power to handle the fan. If you have an amp motor you need to check the amps while the motor is running to make sure it is within the rated amps for that motor. There will be a rating on the nomenclature plate of the motor. The amp rating might be something like 2.6 amps, it may also have a number followed by SF, this is the service factor for that motor, it might read something like 1.5. That means that it is safe to load your motor up to the 2.6 amps plus one half again of the 2.6 amps meaning the total load could be no more than 3.9 amps.
It is always that you have the motor wired wrong, it could be running on the start winding instead of the run winding. So check the wiring and make sure it is right.
You could give us some clues as to what color the wires are on the old motor and where the connected to the contactor and the old capacitor.

esquire1 · Sep 2, 2007, 07:42 PM

I replaced a blower motor in March just to go back 3 weeks and replace again. Had a bad motor. Just because it is new doesn't always mean it is free of defects

hvac1000 · Sep 3, 2007, 03:05 AM

A 960 RPM motor has 8 poles a 1075 motor has 6 poles last time I looked and the 8 pole lower RPM motors cost more money to buy. The lower speed motor was put in that unit for a reason by design. You will have to have a next step larger horse power motor if you are going to use the 1075 RPM UNIT. The reason the bill was going to be high is because that 960 RPM motor is special for that unit and it may have been a ball bearing design. Many times the unit will not work as well if it is changed to a higher speed motor without a increase in horse power rate.

The new motor you have is probably going off on the internal overload built in the motor. This could be a bad sign that the new motor is already damaged.

Good luck with your project.

bubster020 · Sep 3, 2007, 12:44 PM

To answer your question LETMETELLU, the motor I replaced was the one on the inside unit in the furnace. It is an all electric unit. The wiring is like this; blue with blue, red with red, orange with white, black with black, the only one not hooked up is the yellow wire. That is because the new motor doesn't have the yellow wire since it is a 3 spd and not 4 spd, that is what the guy said where we bought the motor from. I am going to look into checkingthe relay with the voltage meter. Hopefully that will be it. The hp on the new motor is 1/2 h.

letmetellu · Sep 3, 2007, 07:03 PM

On some motors the black and the yellow are the line voltage wires, so what you need to do is to look at the wiring diagram on the side of the motor and see if the high voltage leads are black and yellow.
So if you connected the white wire coming out of the motor to the orange wire that could be the problem.