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mtnmn
May 7, 2009, 06:47 AM
I have a Tempstar 5000 gas forced air furnace installed around 1993. The model number is NCC5075BFA1 and the serial is NCC5075BFA1.
My furnace cycles on and off. The air is plenty warm when it does blow. The sequence is the furnace ignites, the blower comes on for maybe a minute or two, the blower turns off, the flame turns off maybe 30 seconds later. After the flame goes out, the blower will turn back on maybe a minute later.
Other times, the flame will stay on and the blower will turn off and on repeatedly. If the blower stays off too long, the flame will then turn off.
I've had the furnace cleaned. When the tech came out he didn't know how to troubleshoot this problem and suggested a new furnace, or perhaps a new controller module if I wanted to throw money at it.
Any suggestions?

mtnmn
May 7, 2009, 07:05 AM
More info on the problem-
The excessive cycling problem is intermittent, the majority of the time the furnace works fine.
And, when it does cycle repeatedly, eventually it settles down and will work fine until the house reaches the designated temperature.
The excessive cycling tends to be prevalent first thing in the morning, so it could be temperature related.
So, the house does get warm, its just annoying on those occasions when the furnace cycles excessively.

Joshdta
May 7, 2009, 01:38 PM
Sounds like you need a new fan limit control.

http://www.high-performance-hvac.com/hvac-photos/HVACPhotos/images/fan-limit-control.jpg

Or


http://www.cozyparts.com/Lennox-Parts/images/13H70.jpg

mtnmn
May 8, 2009, 07:54 PM
Thanks for your advice