My AH 2429-1 heater / a/c is gurgling when the AC runs. There are two drains at the bottom of the pan surrounding the condenser coils, in-side the house. If I remove the filter, remove the front cover or interrupt one of the drain holes, the gurgling stops. Put it all back and the gurgling continues. Why are there two drains? Both connect to 3/4" PVC pipe and lead to a floor drain. One has a trap. I have the Installation and Operating Instructions, and the two drains are not even mentioned.