Furnace.........sometimes

[imported_Dana G.]

Our furnace seems to have intermitent problem. I'd say about 70% of the time it works fine, but the rest of the time the the burner comes on as normal but shuts off after 4 or 5 seconds. It will repeat this process several times before giving up and shutting down as though it had completed the heating cycle. Any advice as to the cause & cure would be greatly appreciated! Or should I call out a repair man?

Thanks

[imported_wbrooks]

Sounds like your flame sensor is bad. check the door covering your blower motor for a wiring diagram and a chart of LED sequences. On your furnace control board (newer furnaces) there should be at least 2 LED's that will flash error codes after and/or during a failure. CHeck the flash sequence againt the chart for a description of the failure

[dietz]

Two possibilites: 1. Like wbrooks said the flame sensor... should be a metal rod next to the ignitor, try some fine steel wool or a business card and give it a cleaning. 2. If it is a 90% furnace you may want to check the exhaust pvc pipe and make sure nothing is blocking it ie: paper, dirt, or the ever popular bird... Slim but still possible the ign. board or module.

hope this helps
Ted

[tomgeer]

Clean you flame sensor w/ sand cloth