Having problems with my Americam Standard air handler. The blower will not always come on. The unit will make a loud humming noise and sometimes the fan comes on and sometimes it will hum and then shut off. The heat pump is working. Had the same problem a few months ago and the technician replaced the time relay board. It ran well until 2 days ago. Any suggestions? Thanks

Your blower motor has what's called a starting winding which assists getting a dead stop motor rolling. Your motor winding could be shot. A little dangerous but you can trick the door to think it is closed, reach inside with a screw driver or stick and try to spin the motor. If it runs fine once spoinning it was your winding. I never shut off my motor, runs 24/7/365 by setting the stat to ON rather than AUTO. This uses just a hair more electricity and makes the home more comfortable, you might just try that.

Would that be something to look at if it will come on sometimes but not others? Thanks!

If it is humming and you spin it and it runs fine then it's the starting windings. They can fail intermittenly but I'd just get it running and switch the stat to ON from AUTO.

No, it hums but can't get the fan to run and it has been on the "on" setting. Since it is cold, I can see the auxiliary heat turn on and then it shuts off after a bit. Any other thoughts? Thanks for your help!

We will try to keep this post alive and hope some other guys will drop by. That was my only line of thinking for the moment, sorry.