Alright, so I monkeyed around where I really have no business.

Motor: 5sme39hl0252 1/2 hp Variable Speed

ECM: GE ECM 2.3 CN03

Original Problem: When I turned on my thermostat this winter, the blower motor was really loud and made a bit of banging. It would then run up to full speed, die, run up to full speed etc. I turned it off and on again and it has since been running at a slow idle. I can feel some air through the vents, but the motor is noisy and it won't speed up.

HVAC GUY: Took nearly a month for the tech to get here and he says either the ecm or motor is bad and to replace both for $1700

Me: Being cheap - I go on Amazon and buy a Genteq Evergreen 1/2 HP 230 Volt Replacement X-13 Furnace Blower (which turns out is a 5 speed thing and not the correct part) However, it fits and I figure who needs variable speed, I'll just have this thing run at 1 speed.

So using my very limited understanding of electronics and HVAC, I install this motor, split common from the motherboard, use the ground and 2 power lines from the original motor wiring and splice into a 24 volt wire which I plug into speed #4.

To my amazement, when I flip the breaker, it starts up, operates quietly and blows a ton of air through my vents. I was very pleased with my hack job... until I realized my thermostat is off and the blower just runs as long as the breaker is on.

Is it possible to get this setup to only turn on when the thermostat is on? Which wire to the motor controls that? Or should I just take this apart before anyone knows what I've done and call for help?