My lennox furnace is blowing out cold air and giving me code primary

Lennox Primary Secondary Limit Switch Open. My Lennox is saying the primary/secondary limit switch is open. No heat The LEDs finally gave a code of "Primary/Secondary Limit Switch Open". Thermostat is fine I think Contractor's Assistant: Do you plan on doing the work yourself? Customer: If I can Contractor's Assistant: Anything else we should.

We just moved into a home with a Lennox G26 Forced Air Furnace After two years the furnace died and it was replaced yesterday with the new.

Lennox G51MP Elite Series my furnace is saying the primary

If I reset it, it works for some time (30 min ~ couple of hours) and then goes off However subsequent times when the thermostat calls for heating, the burners light off and then appear to shutdown due to Primary/Secondary limit. Thermostat is fine I think Contractor's Assistant: Do you plan on doing the work yourself? Customer: If I can Contractor's Assistant: Anything else we should.

My Lennox is saying the primary/secondary limit switch is open. No heat. Before it enters Watchguard mode it gives a 3-1 Red flash code (Primary/Secondary limit switch open) Contractor's Assistant: How long has this been going on with your Lennox furnace? What have you tried so. Starts to blow (lowest speed) and warms up the rooms

My Lennox is saying the primary/secondary limit switch is open. No heat. After two years the furnace died and it was replaced yesterday with the new. Been having a problem the last couple of days where the gas is shutting off after running 5-10 minutes