Background: I bought the house in 2013 with two 5 ton systems already installed sometime in 2003. I contacted the original installer of the HVAC units who is still in business and found most of the information I am about to list from them. The duct-work was retrofitted into the attic by the home owner. All of it is un-insulated in a cold attic, ABOVE the ceiling insulation but the inside of the ducts are lined with sound insulation. The entire house is like that, a real nightmare. The horizontal loop installer is out of business and their locations and sizes are unknown. Well almost unknown. One loop melts part of the driveway, not by design I am sure... The house: Built in 1974, slab on grade, sub-floor insulated with 1.5 inch of vermiculite (NOT from the Grace mine, thank God) 4000 sq.ft. on the main floor and 2100 sq.ft. on the second floor. 2x6 construction insulated with R-20 ish for the most part, some 2x4 with R12 ish in the newer part... Yes, that is right, the 1995 addition is less insulated than the 1974 part. Probably the same guy who installed warm air ducts outside... HVAC equipment: 1 Waterfurnace E series model and 1 Waterfurnace E series model with DSH. The DSH is connected directly to the electric DWH without a buffer tank. Historical issues: I noticed in my first few days of ownership that the lines between the DWH and the DSH were too hot (system running A/C at the time). I figured that was wrong pretty quick and shut the valves to stop heating the ground... I will be installing a buffer as described here before too long as we are soon to occupy the house. Now one of the units is tripping the high voltage breaker. At start up, it will try to start 3 times and then trips the breaker. I was told that the compressor is likely locked up. TX valve perhaps? I already replaced the cap with the appropriate size cap. I also tried a hard start booster cap to only an attempt at a start up. This unit had the upgraded board and a new updated compressor installed in 2007 under warranty. What can I do with this 1o year old unit? I can't replace the TX valve myself, if that's what is wrong, can I? I've installed a few furnaces and can diagnose much of what can go wrong in split AC systems. I am told this would be a $1000+ repair if that was the issue. The compressor has already been replaced once and the upgrade kit put in also for this unit. Any help will be appreciated. Thanks.