there is a kit to fix this. See your dealer and the needed kit. the 'fix' we found was to close the water shut off at the block and then back it out in 1_4 turn increments until the AC would not be overcome by hot water. The problem was the supplier of the thermostat control of the hot water held very poor tolerance thus when it was told to add more water flow it added too little then it called for more and it opened, then it repeated the process on the down side. Any way they did not all do this, just the ones with the faulty valves.