My company installed a broan 3.5 ton heat pump in one of our customers houses just over 3 years ago. Performed a load calc and came out to around 45k btu for cooling so we installed the 3.5. it has worked fine with no complaints until about a week ago he called and said the humidity is really high, his salt shaker won't work, doors are getting stuck, and it's uncomfortable at 75F. So I go over and as soon as I walk in it feels sticky. I check rh and it ranges from 77-85 in his house. 85 being directly above where the air handler is in crawl space. So I go under and the ah is sweating but duct and insulation are dry. About a 4' radius around the ah the ground is damp but not soaked. The rh in crawlspace ranges from 87-92. Everywhere else other than around ah the ground and structure is dry. I checked unit blower speed (ECM) and verified it was set up correct with installation manual. Went outside gauged and checked superheat and sub cool (can't remember what readings were but matched with charging chart. I am going back tomorrow and doing a blower door test to see if we can get to what's causing the high rh all of a sudden. I checked all plumbing and water heater to see if that was the problem and found no signs of water to explain it. It has been cooler low to mid 70s at night and low to mid 80s during day with lots of rain and high humidity, 70-90% for the past week and a half. Any suggestions to look for when I go tomorrow. I hope I overlooked something and it's a plumbing problem but this is a good long time customer and I really need to get it resolved for them.