Gas and Oil Home Heating Furnaces - Limit switch

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lostnspace
12-20-08, 06:47 PM
help? furnace was running smoothly then we got a smoke alarm that goes off next to the cold air return and smells like smoke in that area. I go to the furnace room across the house and the furnace is running but throwing a limit switch code (4blinks).I unplugged it and called the fire dept. but they found nothing only that there infrared heat sensor read 147 f near the blower fan motor.

Skip4661
12-20-08, 06:53 PM
Sounds like your blower motor may have a problem. Start it back up and see if the blower starts.
mbk3
12-20-08, 06:53 PM
was the blower running?...............................

lostnspace
12-20-08, 07:07 PM
okay the blower WAS running and everything was okay before smoke alarm went off. As I was checking everything I see the blinking light on furnace something was running on the furnace but the blower was not. I did try and start it up again and it lit but when it came time for the blower to kick on the light started blinking again .4 blinks for limit circuit switch.
Skip4661
12-20-08, 07:17 PM
You either have a bad blower motor or blower board. A good test would be trying to manually spin the blower wheel. If you have a/c you could switch your thermostat to fan on and see if the blower starts. If the blower starts this way the board is bad. If not the motor is probably bad.
lostnspace
12-20-08, 09:04 PM
Okay i removed the blower motor / squirrel cage and it spins freely by hand is this an indication that the board is the culprit?