Made a sizable investment in a complete Trane XV80 Furnace and XR13 Heat pump system 2 weeks ago. AC failed about 2 days after install. After misdiagnosis- 4 service calls and a new line set- installer discovered TXV on the new indoor A-coil was bad. Installer wants to replace the TXV- is an entire new coil in my best interest? I was told pressure limit switches protect the system, but could other system damage have occured?