I'll try to keep this brief even though it is a long story.
Approx five years ago I replaced an old R22 system with a new Carrier 410a system (38TXA with CD5A coil) for my small split-level home in the DC burbs. Worked OK the first summer but barely made it through the second summer. Since then we've had problems every year, usually the coil freezing up at some point (we're good about the filters). Over the course of numerous tech visits over the last three years we've been told: possible line leak, poor duct design, line should have been replaced when system was replaced, too little refrigerant, moisture in line, etc. Have tried to educate myself about things that can go wrong when replacing R22 system with 410a system, but it is overwhelming. The latest tech came out yesterday because the coil was freezing again (after working well all summer). This time the story is that the system will never work well unless we install a TXV kit ($REMOVED) to replace the piston-type valve that came with the system. Says the TXV is required for Puron systems and the original installers should have known. After dropping $REMOVED last summer on a leak test (no leaks found in coil or compressor) I'm a bit reluctant to drop another $REMOVED on what is essentially a new system. If a 410a TXV is required for this system why would Carrier sell the system without one? After hearing some many different explanations I just don't believe it, even though the tech said he was "100% certain" that was the problem. Can anybody out there tell me if I'm just getting another runaround?