I'm getting two blinks which = 'closed pressure switch'. The only way I can reset the furnace is to disconnect the hose that connects to the pressure switch and some fan looking apparatus and shake out 5 or 6 drops of water from it. Then I can restart the furnace and it will run for between 20 minutes and an hour. I have had numerous furnace repair people out and they have not been able to diagnose the problem. What is the answer, please!