Lennox Elite won't stay lit. Model Number G51MP-60D-135-07

[gregmp79]

My Lennox furnace won't stay lit, there are two slow flashing lights on the furnace during normal operations a red on the left and a green on the right.  When the burner goes out, only the green light continues to flash.  I can turn the furnace off and the back on again, and it will light fine.  But after a few minutes the burner goes out again.  Any help would be greatly appreciated.

Greg

 

[ACtechGUY]

On the panel that covers the circuit board there should be a label that describes what the blinking lights mean. Look and see if you can find it and let me know. I think it means the draft inducer pressure switch opened.

[gregmp79]

It says either the pressure switch is open;

or Blocked inlet/exhaust vent;

or Condensate line blocked;

or Pressure switch closed prior to activation of combustion air inducer.

???

[ACtechGUY]

When it is firing you will be able to see the pressure switch close( The device that has the tube going to it. )

Look at the pin connected to the diapham. It will move away from the microswitch and should stay very far away. If not, then not enough vacume is being produced by the draft inducer fan. This is either because of a rusted out draft inducer wheel, blocked vent pipe or rusted sensing tube inside inducer assembly. I recently saw the sensing tube rust out on a lennox that drove me crazy trying to figure out what was wrong. A hole was rusted on the bottom of the tube(where i could not see it) , and not enough vacume was being produced. You will have to take loose the vent pipe to check out the tube and wheel.

[gregmp79]

I think I might have a blocked vent pipe, I think condensate may have frozen solid in it.

Any suggestions on that?

[ACtechGUY]

WOW!!! NO CLUE. We don't get that cold down here. Try removing the vent pipe and see if it keeps running as a test.