Lennox Merit® G40 Gas Furnace

[vrs]

I have a 2 year old unit. I get the following error after 5minutes of running. Even during this 5minutes, I get no heat.

Out of the 2 LED's, first one if off and second is Slow flash.
Description translates to:
Pressure Switch Opened or has opened 5 times during a
single call for heat, or blocked inlet/exhaust vent, or condensate line blocked(for condensing surfaces only or Pressure switch closed prior to activation of Combustion Air Blower.

What to do next? Its self ignite unit. Any help appreciated.

[a46geo]

Either your exhaust gasses are being blocked from venting to the outdoors, or your pressure switch is being fooled into thinking this is the case.

You must have a 90% efficient furnace if there is the possibility of condensation. Check both the exhaust and intake pipes to make sure they are clear. Kids and animals can both cause problems here.

When you take the furnace vestibule door off, check all of the small plactic tubing for water trapped in any low points.