Author Topic: ECM condenser motor not spinning. Before replacing is there something I am missi  (Read 958 times)

Offline adavid

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My AC condenser unit compressor starts up but the fan doesn't spin.
I took out the fan motor and it's a GE ECM 1/3hp 240v 850/520 rpm. Top of motor has a model number 5sme39hl hy71 and bottom, ECM142 dx05.
Before removing I tried helping it spin with a screwdriver and nada. Once out, I tried spinning it by hand and it's very stiff.
I checked the motor plug at the unit and it's getting constant 240v and 24v once the AC is triggered.
I separated the motor and the controller and checked for resistance and continuity and the motor tests fine.
Interesting though, when I disconnect the motor from the controller, the motor spins freely. When I connect it back again, it's stiff.
This unit does not have any external plugs. Everything is internal and the only outside connection are the 6 wires.
Is it safe to say that the controller is bad or is there something that I am missing or not testing?
Any thoughts about where to get a replacement?
Thanks much in advance for any advice.
https://photos.app.goo.gl/NreQqeGdzec3EBC48

Offline Sergroum

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I'd be a little careful. ECM motors are DC voltage. Which means you have an inverter and a control board controlling your fan. So the issue might not be in the motor, but the module, or the board itself.  It's a little harder to diagnose then PSC motors running off alternative current.

Step number one would be to see the model/serial of the entire unit, not just the motor. Then finding the manual for it. It will likely tell you what kind of DC voltage you need to expect. If what you'll read is different while the wires are still hooked in, unhook them and see if it changes. If they change and become what the manual says they should be, then it's the motor. If they are perfect hooked, or unhooked, then it's the motor. If they are wrong, whether hooked, or unhooked, it's the board.

Offline walker

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its almost always never the motor.  I find 80% of the time the varistor in the module has blown.  20% of the time its the board.

Grab yourself a zebra tester with all the different style adaptors, makes testing ecm a breeeze.  otherwise find the manual and see what signals the motor uses either 24vAC or 9-24Vdc, I'll usually jump the right terminals with 24vAC if its an ecm that uses 24vAC to see if it works, if it does than you know its the board.

Offline Sergroum

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There are motors that tun on 24-46 volt, with 36 being perfect.

Offline maxmechanical

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its almost always never the motor.  I find 80% of the time the varistor in the module has blown.  20% of the time its the board.

Grab yourself a zebra tester with all the different style adaptors, makes testing ecm a breeeze.  otherwise find the manual and see what signals the motor uses either 24vAC or 9-24Vdc, I'll usually jump the right terminals with 24vAC if its an ecm that uses 24vAC to see if it works, if it does than you know its the board.

How's zebra compare to tecmate pro ?

Offline walker

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its almost always never the motor.  I find 80% of the time the varistor in the module has blown.  20% of the time its the board.

Grab yourself a zebra tester with all the different style adaptors, makes testing ecm a breeeze.  otherwise find the manual and see what signals the motor uses either 24vAC or 9-24Vdc, I'll usually jump the right terminals with 24vAC if its an ecm that uses 24vAC to see if it works, if it does than you know its the board.

How's zebra compare to tecmate pro ?

I've only ever used the zebra. So I'm not sure.

Offline williammark

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I will advise you to don't do any R&D just hire a best contractor for that and I also simply do that as compare to time killing and equipment hazards. I have a good contractor in Edgecombe, US for HVAC system and i just go with Comfort Shield HVAC Services