Furnce wont kick on

key failure --ignition switch failure -key sensor is fine ? was it tested or immobilizer failure [rare] your vehicle is not recognizing the key so most common reason is a worn or failed [chip] key

Did you check you crank position sensor?

needs a tune up. flame is probably yellow which means it is burning too much fuel and therefore not getting as hot and it would smell different also.

put a new spark plug in it

ignition failure. insure air pressure switch closes, hot surface igniter is getting 120volts. check continuity on hot surface igniter, make sure all gas shut off valves are open and gas valve is turned on. make sure there is no blockage in the exhaust

no it will cause your furnace not to run at all if the condensate pump fills up

Check your igniter. If the furnce does not light it will do that every time.

Hello, if the burners light but do not stay on for more than 10 seconds, I would clean the flame sensor. The flame sensor is a metal rod that is on the opposite side of the Igniter, sometimes it gets coated by oxidation and does not sense the burner flame and shuts the Furnace down. To clean to kill power to tje furnace, remove flame sensor and clean with a steel wool, then reinstall and start Furnce back up. If this does not work then most likely the Igniter is too weak to ignite the gas and will have ro be replaced.

Remove the cover of the circuit board and controls on the outside unit. Some units have a thermostat that allows you to set the temperature at which it switches to the second stage of heat. Set that for about 34 degrees.

Sounds like it may be a bad flame sensor. After the ignition, the flame sensor needs to send 24v back to the gas valve to indicate the the ignition took place. If it does not do this, the gas will shut of as a safety precaution. The flame sensor can often be cleaned up with a piece of sandcloth to fix this problem, or it may be replaced.