Okay, If you can give me a few minutes, I will check. If there is not a flashing code, what is the best way to reset the furnace. I already tripped the circuit breaker and reset. No change.

The flash code was a 33 according to the chart on the door. Three (3) quick flashes followed by three (3) slow flashes saying it was a flame rollout fault.

Here's what I've done so far. I inspected the igniter, the rod seemed to have a slight carbon buildup on it. I cleaned the rod and replaced. I leveled off the condensate drain pipes (they had some water in them. I blew through the two (2) lines connected to the condensate box until it was clear. I put in a new Air Filter. I inspected the fire box as best I could. The unit is under the house and is partially block by a floor support. The box seemed relatively clear. I don't see a carbon build up or much rust. I tried to reset the flame rollout sensor, but the reset switch doesn't seem right. It feels loose and does not have a definite click like it reset. After all this and turning the unit back on, the heavy duty blower came on and a code 12 flashed on the LED. after a minute, the heavy duty blower stopped and the inducer motor came on for about 30 seconds and stopped. The the flame came on in the fire box and the LED stayed on indicating everything was Okay. The unit ran for most of the night and quit producing heat. The Heavy duty motor stayed on blowing out cold air. I had to shut power off to the unit to shut if off. Tried the same procedures today and the unit started up again. There was a little condensation to clear from the line and I cleaned the igniter again but it looked really clean. I thinking that the condensate box does not drain well and caused the unit to shut down or the the rollout sensor is bad. The problems started with this unit last year when snow drifted up against the outside wall blocking the condensate drain pipe and the unit shut down blowing only cold air. The service techs let the water drain under the house and adjusted the flames because he said it was rolling out. Do you think I should replace the condensate trap and the rollout sensor???

My apologies for not getting back sooner, between work an dealing with the heater unit, the last few days have been hectic. I followed the advise of the roll out switch and the condensate trap and the unit still kicks off after a few hours. I was able to get ahold of the original contractor that installed the unit and they explained it was the heat exchanger and that it was still under warranty. They came out to fix it yesterday but still needed to replace a nozzle on the gas injector so they said. Hopefully all will be aright by tomorrow. Thanks for you help because I learned a few things about the maintenance of the furnace.

I appreciated your help and accepted the answers. Thanks again.