https://bbs.wenxuecity.com/fdcj/1847200.html
Following smlanlord advice, I bought a new control board. I did not open all the doors in the furnace so I did not the exact board #. Furnace is Payne but carrier. different brand from same manufacturer.
https://www.amazon.com/dp/B0CG4NWCJ2?ref_=pe_386300_442618370_TE_sc_as_ri_0
I am not promoting this seller. I order on Saturday or Sunday and was thinking to get it on Tuesday ($40 shipping expense difference), but the seller had it delivered this past Monday.
My 1st time to change the control board (I am a physics majored turn softcore EE. My EE is more on system engineering and networking). 讓行家笑話。 It took me 3 hours to replace the board, double check all connections are correct, test after board change. I should have marked the connections better with pen or label maker.
The original control board was CEPL 130438-01, not even on the replacement board list of what I bought. They are all drop in replcement of HK42FZ013 so I changed it any way. Pretty much like pc motherboard change with a lot of external connections.
Other than Error code 33 showing up only 15 minutes during final testing, everything ran fine. But error code 33 (13) came up again overnight. After circuit resetting, gas heater ran fine again. I ordered a pressure switch and roll out switch, but to make tenants more comfortable I decided to let pro came 2 days later.
He found blower motor capacitor capacitance dropped to less 1uF from 7.5uF (he almost missed it). For me it is $250 training class with a gift of $10 capacitor (capacity $150+ trip fee of $99). It is worth it. For this guy, it is about 3 hr including travel time. He taught me how to check fame sensor with current measurement (1-10 uA). Gas heater ran fine after the capacitor change. This guy "broke" exhause pipe and rebuilt it in a rough way.
One way to check if the furnance is overheating to check temperature rise (from inlet to outlet/vent). 30-60 F is normal. Spec is on cover. Need to worry it is above 80 F. Some furnace temp rise could be as high as 75F.
There is another posting I saw but I could not find it now. Bad gas valve triggered flame roll out switch. In my case, blower motor may be slow to start and triggered high temp switch.
I wrote this long posting so other people can learn an save money. control board lifetime 10-15 ys. He said blower motor capacitor could be as short as 5 years.
A lot of good discussions at
https://www.diychatroom.com/search/533387/?q=HVAC&o=relevance
