Been an exciting few days around here. I posted a while back with a blower that didn't run and I thought a diagnostic code, but I was looking at the wrong LED. The diagnostic LED never showed anything wrong. It's a Trane XV80 air handler with variable speed blower. And the blower varies it's speed constantly now.
It's one of those annoying intermittent problems. It works fine late night and early morning, then in the afternoon it starts. The blower seems to startup and shutdown constantly. Sometimes pausing a few seconds and then starting up again, only to stop half way to full power and ramp back down again, then startup and run fine for a few minutes and ramp down to half, then back up to full. and over and over.
The HVAC tech was out this morning, but of course it wasn't doing it then. He's ordered a new motor for me which should be in in a couple of days, until then it continues to cool OK in the night and less so good in the afternoon under high load.
My worry is that it will quit entirely and damage the outside compressor which appears to continue to run while the blower goes up and down.
Has anybody heard of such a thing and might have some further advice I can pass on to the tech? Is there a way to see if it's the motor or the control board? Right now he's just ordered a motor, but he didn't really know about the board. I asked him and he said that the controller was inside the motor. But I dont' think thats the case, or you wouldn't need so many wires running out of the motor.