Upon arrival system was off. Inspection of unit shows that 20x25x4 air filter is very dirty. Replaced with new 20x25x4 air filter. Ground loop pressure is at 0psi when it should be between 40-70psi. Current loop pressure testing ports are hard to work with and risk damage to tools during testing. Pressurized up to 40psi from house water supply. House water supply was only at 40psi so it could not get any higher than the 40psi. Performed a test run in cooling stage 2 to check for any other issues and to let the ground loop solution properly mix to get a proper freeze protection reading. With proper ground loop pressure and clean air fliter, the cooling was operating within air temperature drop, ground loop psi drop, and ground loop temperature increase. Did not check refrigerant as there are no issues suspected. During test run, found a leak in one of the fused fittings on the ground loop system. This will need to be repaired to prevent loss of pressure and antifreeze in the system. Aft