My 20 year old Carrier Weathermaker is leaking water at the rate of about two cups a day from inside the unit. The tech came and looked at it "thinks" that the heat exchanger is cracked since the drain tubes are absolutely free from debris. Every three days I go mop the water. For the last two days it's been VERY cold.4 degrees here in Boston. The furnace's fan is working, the flames are coming out of the tube (I can see through the glass peep hole)into the exchanger but I notice that they are a little yellow and are a bit wavy (not flowing very strong into the exchanger), water is still leaking BUT the air coming out of the registers is warm, not hot like it used to be. The furnace has been running and running for two days and the house can't get above 62 degrees. (It's a 4 zone system)Any idea's??? I think I may need a new furnace but I don't want to spend $8600 if I am not sure. THANKS!!!