My furnace kicks on, runs for a few minutes then kicks off, then right back on...WHY?

It's the sensor/relay that turns the fan on and off. It is starting the fan at too low chamber temperature.

Its a dirty flame sensor. its a little metal rod that sits directly inthe path of the burner flame. take a 1/4 inch nutdriver and remove it. Scrape the metal rod part with the EDGE of a piece of cardboard to clean it up-Careful not to touch the metal rod with your fingers. reinstall it.

That will fix the furnace problem.

Get rid of the open box of laundry detergent that is nearby-that's what causes it.

i think of it desires a checkup. something is out-of-whack, yet i do no longer understand what it must be. verify to work out that there is no longer something heat close to the thermostat that should impression the temp of the thermostat, exchange the filter out, make optimistic a circuit breaker hasn't tripped. this is all the difficulty taking photos techniques I even have, yet i do no longer think of they're going to restore the concern.

if you have a 90% efficiency furnace it is purging its self

the first run normal