When my heat would not come on, I thought it may be the pilot light. I followed the instructions and the furnace fired up. However, when the blower would normally start, the unit turns off the burner. The diagnostic light inside the unit indicates "blower circuit open". Is this something that I can address or do I need to call a professional repairman?

What type of furnace does it have a board with the blower relay built in and does the blower turn on when the flame goes out if it does then jump out each limit switch one at a time but most likely the high limit would be the problem. Let me know Mikie D.

If you have a volt meter you need to use it on the leads going to the motor to make sure that the motor is getting power.

But first with the furnace unplugged try to turn the squirrel cage, if it does not turn easily it could be the bushings in the motor, if it turns easily it could be the capicator.

Are you sure that isn't "limit circuit open"? What is the model #?