furnace exhaust motor

[bobs]

Furnace exhaust blower motor cycles on and off continuously between the normal heating cycles. any ideas? This is happening on a Goodman Model GDP1075-3 , 80% efficent about 15 yrs old. I replaced the flame sensor with a larger type about a week before it started doing this.

[HayZee518]

blower must cycle off a stack temperature device. flame sensor doesn't have anything to do with the exhaust gases. its function is a flame detect safety device to keep your furnace from blowing up should the pilot go out and the main valve stay open.