Have a coleman furnace eb12b

[gitterdone]

Seems it is getting louder when it cuts off. Blower motor that is.

I know they make some noise when cuts off..

But seems it thumps hard here latley.

Reply much appreciated.

[gitterdone]

Never mind... either duct work exspanding when blower is on..turs off thump duct work/plenum settles back.

Or lower speed switch is bad. Fan cuts off on high.

[Shootist]

It's probably your return plenum sucking in from the vacuum and popping back out when the blower stops. Try putting a heavy box or a few bricks on top of the plenum. Also make sure your filter isn't getting stopped up. A dirty filter will create even more vacuum.

I've also seen loose fitting filters in ceiling grills rise up and then drop when the blower stops.

[gitterdone]

Thanks man.for the reply...Filter alway checked...going to look at plenum ..might need a few screws ect.