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Heating, Air Conditioning, Fridge, HVAC/American Standard Freedom 80 Blowing Cold



I have been having the same issue with my American Standard Freedom 80 furnace for the past two years.  It will run for a few cycles, but then time out.  The blower keeps running so it feels like it is blowing cold air-- but the burners are not running.  The error code is two blinks-- "system lockout. No flame. Check line polarity."

Last year I had a repairman replace the thermocoupler and the flame sensor.  I took steel wool to the flame sensor to buff it up, but still no luck.  He wants to replace the circuit board.  

Because that is a big bill, I am looking for outside advice without the $90 service charge, since that is money already spent.

Any advice would be very appreciated!

Replacing the control board can be a hard call to make.  It seems to be working, but then it fails again at some point.  At this point if everything else with the unit checks out then by all means replace the control board.  I would make sure and keep the old one just in case the problem reoccurs and it is determined the board is not the problem you still have a good working board.  Sometimes those working on units misdiagnose things and the actual problem is something else or a bit harder to find.


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Craig HVAC Expert


I have been in the HVAC field for the past 18 years. I can help with most HVAC questions. I work on commerical buildings for the most part, and have yet to find anything I could not troubleshoot and repair, when repairable. I work on small 1 ton units to a 2500 ton chiller. Troubleshoot air flow, elect, and control problems. I attend regular classes to keep up with the latest and greatest.


I work on commerical sites, hospitals, gov't buildings. I can troubleshoot just about anything in the HVAC business.

5 years trade school, VFD training classes, Liebert factory training, some York and Trane factory training.

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