It runs for a few minutes, stops, and starts again

Still in play

Everything on the list has been ruled out. That is a genuine result: it means the cause is almost certainly inside the equipment — a control board, a sensor, refrigerant charge or a failing component — and it needs somebody with instruments rather than another thing to check.

1. A restricted filter. The commonest cause by a wide margin. On a furnace it overheats and trips the limit; on cooling it ices the coil and the pressure switch stops it. Change it and watch for a day before doing anything else.You can check this
2. Closed or blocked registers and returns. Closing vents to "save" an unused room raises static pressure across the whole system. Furniture over a return grille does the same thing and is harder to spot.You can check this
3. The thermostat is reading the wrong thing. Sun on the wall, a supply register blowing at it, or a cold outside wall behind it all make it satisfy and call again quickly. Moving it is a real fix, not a workaround.You can check this
4. The outdoor unit cannot reject heat. Cottonwood seed, leaves, snow, a fence built too close or shrubs grown in. The unit builds pressure and cuts out on its own protection.You can check this
5. A blocked or restricted flue or intake. Birds, snow, ice, or a screen that has silted up. The pressure switch will not stay made and the sequence stops part way. This one is a safety item rather than an inconvenience.You can check this
6. A dirty flame sensor. Very common, very cheap. The burner lights and then the board shuts it down within seconds because it cannot prove the flame.Needs a technician
7. An overheating heat exchanger, or a cracked one. If the limit is tripping with a clean filter and open vents, the airflow across the exchanger is wrong or the exchanger itself has a problem. This must be looked at properly, not reset repeatedly.Needs a technician
8. Refrigerant charge, high or low. Both cause cycling, for different reasons, and neither can be judged without gauges and temperatures. A system low on charge has a leak; topping it up without finding the leak is money spent twice.Needs a technician
9. A failing capacitor, contactor or pressure switch. Electrical parts that fail gradually cause exactly this pattern before they fail completely. Usually inexpensive if caught at this stage.Needs a technician
10. Defrost control behaving badly. A heat pump going into defrost far too often, or coming out of it too early, looks like short cycling and is a control or sensor problem rather than a mechanical one.Needs a technician
11. The equipment is too big for the space. Oversized equipment reaches the setpoint quickly and stops, over and over. It is the one cause on this list that cannot be repaired — it is fixed at replacement, by sizing from a load calculation rather than from the old nameplate.Fixed at replacement

Stop and treat it as urgent if a furnace locks out repeatedly and will not restart, if you smell burning or gas, if a breaker trips more than once, or if a carbon monoxide alarm sounds. For a CO alarm, everybody leaves the building and you ring 911 or the gas utility from outside, before anyone rings us.

Whatever the cause: repeated resetting is not a repair. Each reset puts the equipment through the start it has already failed, and the thing the safety device was protecting is still there.