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ECM 3.0 motor speed controls

I have an old HVAC blower motor which was removed from a Carrier air handler on grounds it was defective. It's half horsepower, with ECM 3.0 controls. It has an AC input for motor power and a four pin control connector marked common, Rx, Tx and V+. Physically it's in perfect shape.

On the bench it seems to work fine. The test procedure applies 24 VAC between common and Rx, the motor soft starts and runs smoothly.

I'd like to adapt the motor to other uses and if possible exploit the variable speed feature, but there's no info readily available that describes the control signals.

There's a YouTube video at

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a physical teardown implying a digital interface is used, but no electrical testing is shown.

Does anybody have further information that might be used to communicate with the controller?

Thanks for reading,

bob prohaska

Reply to
bob prohaska
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If you have access to a working version of that motor attach a scope to Rx and Tx. At least I managed to find out how to control a blower to mix gas and air with my central heating.

Reply to
albert

The test I used consisted of merely applying 24 volts AC between Rx and Common. How that can work via a digital input eludes me. I don't have a scope. Can you describe what you did to control your motor? I gather certain "smart" motors have dual-use inputs. While I have the running motor I do not have access to the equipment it came from so It's impossible to see what signals were in use.

Thanks for writing!

bob prohaska

Reply to
bob prohaska

The blower was working in the central heating system. The power pins were just 0 and 24 V, permanently. It took some effort to attach a thin wire to the control pin. Then is become obvious that it was a pwm signal of 2 Khz, with the width controlling the speed of the blower.

Reply to
albert

Motors marked X13 are known to take PWM inputs. Mine is marked ECM 3.0, how was yours marked?

Thanks for writing!

bob prohaska

Reply to
bob prohaska

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