Customer has 1 y/o RunTru system that operates for main level. Furnace located in crawlspace. System was not heating due to water in vinyl tubing of inducer motor blocking pressure switch from closing. Cleared vinyl tubing. Informed customer that furnace is incorrect application for crawlspace. Should be 90%+ 2-stage equipment. Possibility of water being fed back to inducer motor from flue venting on roof. Customer will have roofers check for proper roof cap. Noticed during inspection that system has no form of water protection. Recommend drain line replacement. Replaced 14x25x1 filter. Informed customer of findings and recommendations. System is currently working.