Having an issue that just started recently with our Carrier 58GP Series 100 furnace. At first it had the symptoms of a bad limit switch, furnace would turn off, blower off, then blower back on and off. I didn't replace the limit but am now having a different problem, the blower won't shut off (The flame will come on when it's supposed to).

I'm attaching the electronic schematics:

http://img51.imageshack.us/i/img1549p.jpg

I've done some troubleshooting and am almost certain that it's not the limiter. I've disconnected Lim-1 wire and Lim-2 wires blower remains on (no voltage on GH).

Just by looking at the schematics it seems to me the HFR or CFR relay is stuck on but I can't seem to get them to open.

What steps should I take now? Should I just buy a new control board?

Thanks

Your image file does not work at image shack.

Disconnect the G wire on the furnace therminal strip and run it. Report back. If this fails it might be the board.

I've disconnected all the thermostat wires to no effect. Looks like I'm going to go get a new board at lunch.

Good thing I posted the wrong link as it was the wrong photo anyway. =) Here's the right one.

http://img683.imageshack.us/img683/4906/carrier.jpg

Changed out the controller, seems to have done the trick.

Good deal. Glad you have heat