York Furnace won't heat up. HELP!

I have a York furnace (model P4HUC16N09201A) that will not throw out warm air. The ignitor heats up, the gas kicks in that the flames go for a few seconds. At that point, the flame shuts off and the blower kicks in.
The flashing LED says that the rollout switches are the problem due to various factors.
I pressed the reset button on each rollout switch but none have been tripped. I also followed the schematic diagram to the first roll out switch in the series and bypassed the entire string. This resulted in the same problem (burners off with the flashing LED).
Do you have any other ideas about what could be the problem?
Thanks in advance.

 

Is there a different flash code for flame failure or failure to light? Because that is what is sounds like, a failure to sense the flame after ignition. You can try to clean the flame rod, it is a small rod held in a ceramic insulator on the last burner away from the ignitor, usually held by a single screw. Use a Scotchbrite pad to clean it and also clean any wire connections as well as any grounding jumpers.

Post back.

 

The flash code indicates a rollout switch issue. There is a different flash sequence for the flame sensor. I cleaned the flame sensor and it didn't help.

 

Check to see if the chimney is completely clear, also the fire side of the heat exchanger. That's all I have to offer, sorry.

 

I'll check these two. Thanks for your time

 

If you had a flame rollout issue..... you should see flames coming out of the burner area.
It should be very easy to see.

You're getting 5 red flashes ?

 

Yes, I'm getting 5 flashes. The manual says that 5 flashes means that a rollout switch has tripped. This is not the case.

 

Faulty switch would be my guess. do you have a meter to check it?

 

I am not familiar with your furnace but I do know that some furnaces have, or did have, a self-resetting flame rollout safety switch. These were for minor rollout events that were not of sufficient size to trip the manually reset rollout switches. If your model has such then it is possible to trip on flame rollout and not trip the manual resets.

Rollout is caused by a few different things, if this is an "atmospheric" burner, one that does not have an induced draft blower, then the most likely would be a partially obstructed heat exchanger with an obstructed chimney being second. A third possibility would be a "hard" light off and this is often caused by dirty or damaged burners, either the pilot or main burner. My old furnace would sometimes light so hard it would blow the service door off of the cabinet. That was due to damaged burners that would have cost about $600 to replace (parts only) on a furnace 18 years old. I elected instead to have a new furnace installed rather than have new burners in an old furnace.

Check the burners for dirt or plugged orifices. Especially check the alignment and cleanliness of the "runners" between burners that "pass" the flame from the first to the last burner.