We are also having the same problem as Mike Zenner and Dave Dougherty only we've had the problem on and off since 1996. (Our furnace was is 4 years old then.) We've had the repair guy(s) out about 5 times. They've replaced a circuit board, cleaned, and many other misc things. Total cost for repairs (not including a new blower in 2001) has been around $400.00. Any suggestions here?