I have an Amana central unit made in 1996. I have no
24v out of the control board to the thermostat. The return
Air blower runs all the time and I can only stop it by pulling
The main fuses. I replaced the control board but it
Still does the same thing. Any help would be greatly
Appreciated. Mike

Is this a furnace?

Model number?

Yes it is an amana furnace.
Model number is PGB36C0902D
It's a gas package

Look at the wiring diagram on the back of the door the goes to the control area of the unit. See if you can find the high limit control switch and any roll out controls switches.

Turn power off and see if the high limit has a reset button on the control (it might be in the center of the flat disk type limit controls.

I think your unit might have over heated and kicked the limit or other controls out. On most units that will keep the blower running without the unit firing.

Thanks, I will check it out. Should the high limit and roll out
Switch be normally open switches?
Thanks

All your limit switches should be in the closed position. Only your vent and flame roll out limits should have to be manually reset. Your main limit will reset after cooling down. You should have a flashing light inside the blower door telling you what's wrong. Look through the small glass window on the blower door and count the blinks on the control board.