Expert: mike newberry - 2/5/2009

Question
Based on LED error codes (model G40uhx), either:
1. pressure switch is open or has opened 5 times during a single call for heat
or 2. blocked inlet/exhaust vent
or 3. pressure switch closed prior to activation of combustion air inducer.

Just wondering if I can fix any of this myself (esp. blocked vent) or if I should just call for repair.

sounds like blower kicks on but then no heat and system stops after 45sec-1min.  Just broke overnight; temps dropped to 20F outside.

Answer
Your pressure switch is either bad or you have a bad tube going from the pressure switch to the draft inducer or your vent is blocked. Take the small tube off the draft inducer and suck on it to see if the pressure switch moves. If it does you could try the furnace again and watch the switch to see if it moves after the inducer comes on. If it does and the furnace won't light you will need to check the switch with a meter or you can just buy a new switch they are not that expensive and see if the new switch solves the problem.