At the end of last Summer I noticed some water coming out from under the furnace. I opened it up and saw that the drain hose was plugged up. I got a new hose and put in new 1" pvc, plus a pvc trap as I quickly learned that without a trap the hose sucked air into the furnace, thus, no draining. After installing the trap there was still a bit of water coming from under the furnace so I found out that the coil fins were a bit dirty. I cleaned them with two cans of cleaner but now wish to do it again before a/c season. What is a good product to use and what is the best procedure?