York Heater Comes On Intermittently When Thermostat Sends Command

I have a York Stellar natural gas heater, model #P1UCD12N07601A that’s about 22 years old. The problem that I’m having has been intermittent for about 3years. When the temp drops and the thermostat switches the heater to turn on, it fails to turn on. The thermostatis a Robert Shaw digital non- programmable. We hear the click on the thermostat and the fan symbol is spinning on the screen of the thermostat.

Once this happens, I go to the basement and reset the power switch at the unit. Sometimes I have to flip the switch a few times. Then the blower turns on and the proper sequence begins.

The fact the unit runs properly after resetting the power switch at the unit, leads me to believe the thermostat is sending the correct signal or voltage.

Is there a relay or something else sticking?

 

Take the cover off and watch the furnace during a bad call for heat.

Does the venter motor come on?

Does the igniter glow?

Here's the manual: http://www.hvacc.net/pdf/upd111507/R...ut%20-1288.pdf

If you haven't gotten it looked at in the last couple of years, call for service.

For others viewing this thread, it's an induced draft (80%) furnace with hot surface ignition, not natural draft in spite of being 22 years old..

 

During the bad call for heat the venter motor doesn't begin. The igniter doesn't glow. That's when I flip the ac switch mounted on the outside of the unit. Then the venter motor begins and everything is normal thereafter.

Two years ago, I had a service call performed. The system never failed the entire time the tech was here. This is a very intermittent problem, but I fear leaving the heat on, when I'm away from home.

Two days ago, I replaced the hot surface igniter, because the old one wasn't glowing bright enough to ignite the gas. The new igniter is working great.

Thanks for the manual.