Does a york diamond 80 furnace have a pilot light?

Is the igniter receiving 120 volts after the pressure switch closes? If not, either the board is bad or the pressure switch is open

try jumping out the pressure switch see if this works

You need to clean the sensor with steel wool so its very clean check sensor connections . If it is still not working you could change sensor also check out the pressure switch .

The furnace is not sensing the flame. Turn off the power.
There is a metal rod in front of the last burner to light. It is corroded and needs to be cleaned. Its the flame sensor .
take the 1 screw out holding it in to the bar and scrub it with some steel wool till shiny. replace and turn on furnace. all should be fine.

Had the same problem. The heat quit during the night leaving the fan blowing cold air only. Ah, Looked online yesterday at all that came up in various forums. Not once did I see the suggestion "Replace the Glow Plug" which I suspect is common in a 6+ yr old "York Diamond 80" - Not very helpful, guys...Cost for part was about $22. I paid a handy local another $40 to diagnose, locate & purchase the plug, remove & replace the plug. If you want to continue to attract advertising to these forums I think you need to turn down the obfuscation & engage your experience & be a lot more forthcoming with known common solutions instead of the whirling around all the "it could be's" Seems to me to be an effort to intentionally withhold and not to be too helpful while pretending to be offering a worthy place for the homeowner to discover that you guys charge gravy flat fees for things anyone with a common set of tools & a bit of honest guidance could do himself. I know, it's a dog-eat-dog world & baby needs new shoes but unless we all start actually helping each other this world is gonna keep getting worse for yours and my kids futures. Self-interest has got to be seen in proper perspective, not from the view of The Law of The Jungle mentality that has taken us to the brink of inhumanity. It was NOT this way in "The Greatest Generation" my Fathers world. In that world The Bastards were the exception not the RULE!

how can I fix the spill limit switch, also how do I found it

Bad or dirty flame rod or burners.

On a call for heat, the 24 volt thermostat sends a signal to the control module. The control module will indicate a call for heat with a light on the control either blinking or remain solid depending upon model. The inducer (exhaust) blower will purge all gasses from the furnace and pressurize a pressure switch. Once the pressure switch tells the module to continue, the electronic ignition will energize and send 120 volts to the igniter. The igniter will glow and you will be able to see it if viewed thru the small inspection port. Once the igniter gets hot enough, it sends a signal to the module opening up the gas valve (24 volts). Either a pilot will come on or the burner tube will ignite then spread the flame to all burners. Lastly a safety sensor will be looking for a certain temperature within a few seconds and the furnace will continue to operate and the room air blower will turn on in a minute or two.

What could go wrong? The unit will not run if there is no signal from the thermostat (bad thermostat or broken wire), the control module does not sense a signal from the thermostat (bad control), the inducer does not energize (bad motor), the pressure switch does not close (blocked vent piping, bad switch, plugged condensate hose), the igniter does not energize (bad control, bad igniter), the gas valve does not open or there is no gas (bad gas valve, broken wire, no gas), the pilot does not light (dirty pilot), the burner does not light (bad burner, plugged orifice, not enough combustion air), the flame does not spread to each burner (bad flame spreader, dirty flame spreader, more bad burners), the flame safety sensor does not detect flame (dirty or bad flame spreader, bad flame sensor, broken wire, bad control), or the room air blower does not energize (bad fan motor, bad control).

mine too

The flame sensor might have dust build up on it. The flame sensor makes sure that the system has ignited before it starts the main blower. If it ignite and burns for 15-20 seconds then goes out that is most likely your problem. Identify a probe that is in the direct path of the flame(usually in the last burner tube from the gas source), it will have one wire coming off of it and usually has one screw holding it in place. As time goes by the sensor will get a build up on it and stop functioning. Turn the power to your furnace off, then remove the screw and then gently pull the flame sensor out. Using a MILD abrasive like panty hose of paper towel (DO NOT USE sand paper) clean the sensor and then put it back into place. Tighten the screw and then turn your furnace back on. That should fix your problem.

time to call service guy you are cycling on a saftey which means somethings not right in ignition circuit the only thing i would tell a untrained person to try is cleaning the flame rod which is part of the pilot assembly it is a metal rod that gives small electric current to ignition device confirming that you have a pilot lite you can lightly sand with sand cloth