In about the 2017-2018 time frame the York Affinity YP9C 97% modulating gas furnaces with a white-Rodgers 36j27-508, York S1-02543257000 modulating gas valve started showing flame lockout messages on the smart thermostat. This is caused by one of the two main valves in the unit sticking closed. This event happened to me twice - once in Feb 2018 and again in Feb 2013 - both times in the middle of the night. THERE IS A DIY SOLUTION!
Turn the power to the furnace off. Turn the power back on. The furnace startup diagnostic runs and communication with the smart thermostat is completed. After a couple of minutes, the exhaust injector blower starts for 45 seconds then the ignitor energizes and the gas valve is actuated when you should hear a click. When you hear the click sound firmly TAP (not hammer) the valve 4 or 5 times at the top right corner of the metal body portion of the valve above the output gas pipe with a very small ball peen hammer. Soon you should hear the gas igniting in the burner. I did this in 2018 and the valve operated normally for 5 years. In 2023, when it happened again. I did the same thing and the valve started working normally again. Subsequent Rev letters of the valve like Rev D incorporated a fix for the valve sticking issue.
Hope this info is helpful to others who experience a sticking White-Rodgers modulating gas valve.
Our company actually stopped installing the York Mods because of the gas valve issues we would have with all of them. York started getting annoyed with us having so many changed under warranty. It's just a bit difficult to show up at a service call and charge the customer with a fix where we tap it a few times with a hammer and hope it's fixed.
I've also seen these gas valves come faulty from new where I can't get the gas pressures low enough to dial in the low fire and high fire to spec. The small potentiometer will do a full rotation back to its highest setting after you've reached your lowest point and the process just repeats itself.
Before I figured out the tap method for unsticking the valve, a local hvac company quoted $800 to replace the valve. In 2018, the valve was $169. $631 for a half hour of work to replace the valve seems ridiculous. Oh, plus tax!!
I work for a York dealer. Luckily all our mod customers are on the parts and labour. The gas valve thing is rampant. One thing I've heard was actually a voltage issue that York boards were messing with the valve. The other large problem is the intake pipe being situated directly above. In the summer that ridiculous humid air comes in and wreaks havoc. (Door switch issue anyone? A definite lesson in dew point).
Quote from: DaveTF on March 06, 2023, 01:54:49 PMBefore I figured out the tap method for unsticking the valve, a local hvac company quoted $800 to replace the valve. In 2018, the valve was $169. $631 for a half hour of work to replace the valve seems ridiculous. Oh, plus tax!!
It would be more than a half hour to install, properly test and dial in pressures with a manometer. The service tech has to source and get the part from the supplier (which can be a lot of fun sitting on the phone waiting). We have to drive to and leave your home and fill out a pile of paperwork after the job is done. These are all fee's that need to be accounted for as I'm sure you don't have a job where you're required to work for free throughout an 8 hour day. There's realistically no job I can do a service call on and charge less than 1 hour. If I have to show up just to flip a switch, I still need the full hour to have a chance fill out paperwork, drive, and complete other remaining calls to make an 8 hour day. But I agree, that price seems steep if the valve only costs that much.