I was called to a home to inspect a customer's air conditioning unit. Upon arrival, I noticed that the system was cooling, but the customer was concerned about her electric bill and thought there might be a leak in the ductwork. I went up into the attic and inspected the ductwork. The attic was very tight, and there was very little space to move around the air handler unit. There was ductwork and joices right in front of the unit, making it almost impossible to open the doors. After inspecting the unit, I found that there was a supply plenum leak, which was causing a lot of air to escape. I taped it up with spray adhesive and sealed it up all around. I also noticed that the customer had another gentle man modify the ductwork, which had caused the supply plenum to almost come off and leak air. I told the customer to put traps or get pest control to find a solution to keep the critters out of the attic. The customer paid $79 for the diagnostic fee with a credit card for today's service