AC Vent Fan only operates at high speed setting on 2003 Honda Accord

My 2003 Honda Odyssey has a variable speed fan. Until last week it was working fine. Now it will only come on when I turn the dial up to full speed. As soon as I back it off from full speed it turns off. It will also come on at full speed when I turn the setting to Auto. Any ideas what went wrong?

Asked by for the 2003 Honda Accord
Most likely is the blower motor power transistor is bad. It's mounted in the HVAC assembly to the left of the blower motor.2 philips screws.
1 more answer
blower motor resistor is bad