I have an intertherm furnace, and sometimes it cycles just fine, while other times it will do this:
Ignition coil warm up
Gas turns on and starts to warm up furnace
Gas cuts off just as blower winds up
Blower runs, blowing cold air through the house
Blower stops

Then this cycle repeats itself.

Any ideas?

Thanks!

You could have a defective fan control sometimes called a fan and limit control on some furnaces. If this furnace is in a mobile home the you probably have a disc style control that has two wires attached to it. If you have a mobile home please visit the site below and list you problem under Nordyne. They will answer your question and help you find the correct part and part number for your unit. They also have parts available to make it easy to get and delivered to your door.

Index page (http://www.mobilehomerepair.com/phpbb/index.php)

Thanks for the reply! It's in a standrard bricks and mortar house on a slab though. How does this change things? Also, is this an expensive repair?

So after doing some looking around, it seems that Intertherm furnaces tend to go in mobile homes rather than regular houses. Is this a major issue and does it need to be replaced right away or will it be OK for the time being?

It is always better to replace the defective part asap so the furnace goes back to working normal OR it stops working all together.