Furnace does not cycle after running 15 minutes

[j9m5]

Furnace has been working for two years. Same thermostat.

Now: it will run about 15 minutes. then stop... 

power off, on again, and it will run 15 minutes... 

During the weekend it worked fine.

Last few days,  back to stupid.

Replaced the thermostat with an old mechanical.  Still no joy.

Replaced the filter,....

 

 

[Atomic57]

Do you have easy access to the furnace? The sequence of operation is almost the same as a gas dryer. Your draft inducer motor will turn on. 2. draft inducer motor will close the flu pipe pressure switch. 3. All other safety switches will be tested, if all switches are closed the ignitor will turn on. 4. gas valve will open and flame sensor will keep gas valve open, if flame is being sensed. 5. blower motor will turn on about 15 to 30 seconds after gas valve opens. If furnace is running and shuts off, do not turn power off, reset, or pull the blower housing panel off. There should be a clear plastic opening on the blower panel. Need you to count the the flashes on the control board, this is your error codes. There should be a sticker mounted the panels that explain what the error codes are. If you do not have a sticker we can easily find what codes are, I just need brand of furnace, model, and serial number. Air conditioning and heating are easy to pull manuals and get tech support. Even home owners can call tech support for help, not like appliances.