Okay--I checed the blinking LCD and get a Code 31 Error, which says to check for a number of things but I think its this:
Defective Pressure swith or connections. The reason I say that is because right after that, it says, "If it opens after trial for ignition period, blower will come on for 90 second recycle delay."
Now that's what happens with mine. If I reset the door switch (i.e., just push in the switch that would be pushed in if you put the service access door back on), the heater comes on for 90 seconds and then shuts off. This problem was intermittent for a couple days--the heater would come on later at night, but now doesn't come on at all.
Is there any way to check for that/fix? If I need it a repair, what should it cost?