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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 21995
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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Hello, I have a 6 year old Centurion (york) furnace model FG9B08012UP11C

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Hello, I have a 6 year old Centurion (york) furnace model FG9B08012UP11C Iam currently getting an error code of 4 red flashes. not sure what to do at this point. I tried turning off the unit to see if it resets, tried changing air filter to alleviate air restriction.I am also getting a smell of what seems like a wire or plastic burning. any advice would be great. Thank you Alan



Can you tell me if the main blower that blows air out of the registers is running?



Customer: replied 5 years ago.
Yes it runs but seems to delay start up . it starts shorly after the heat element shuts off. then the element starts up again.

The code is for an open high limit.


Common causes are dirty filter, bad blower motor, plugged ac coil (if equipped)


Short story is the furnace is running too hot and is needing to shut down on safety and cool off...then it tries again.


If filter is clean and no registers are blocked I would recommend checking the blower for proper air flow.



Customer: replied 5 years ago.
I do have an ac unit equipped where do I check to see if that is plugged?

This depends on the installation. It almost always requires the removal of the coil or sheet metal encasing it.


If the unit has always had good filters it is unlikely...but if the unit had a history of dirty filters then the ac coil is suspect.



Customer: replied 5 years ago.
i have used the 3m versions of filters almost exclusively (1-2 exceptions) for filtration purposes. the blower starting up, even a little late, does that seem more likely? I just started it up again and when i heard the "click" for the blower motor to engage I touch (wiggled) the black wire from motor to circuit board and it started. no error code this time. Could it be the board ? Bad connection?

You are most likely correct. Tighten any connections...use a pair of pliers to gently crimp slide on terminals.


You may also have a bad spot in the board.



Customer: replied 5 years ago.
Checked all wires connected to board and seem good, however i did find one wire of the two that connect switch from motor was off. Re-connected it and am doing another system restart. Upon re-connection i was still geeting an error code of 4 flashes. It hasn't ran a complete cycle yet . will it reset itself? should I do something or just wait a cycle?

Wait to see if it resets. Once cooled it should start again. In the event the limit becomes stuck you can try tapping it. It is located on front wall behind gas valve and has 2 wires attached. It mounts directly to the front wall.



Customer: replied 5 years ago.
Seems to be all set no error codes and no smell of any concearn. will periodically check so as to be in the know.I appreciate your help and advice in this matter. Thank you very much, Alan

You are very welcome.


The good news is that your furnace is very sensitive to safety related situations. It will let you know if there is a problem



I wish you luck....



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