I have a Trane 4txc coil over my furnace. On the coil there are markings for P and S with PVC pipe coming out. The S PVC runs outdoors and the P appears to go into the all and connect at my kitchen sink drain. I noticed the outdoor S drain is dripping water. Does that mean the P is clogged? I am assuming P is primary and S secondary. My wife clogged the kitchen sink this morning but I plunged it and all of my drains are draining normal. Is it bad when the S pipe is dripping? And if so how do I unog the P?