The use of TXVs changes the way technicians charge residential air conditioners.
If you don’t understand refrigerant metering, liquid refrigerant coming from the outside (condensing) unit is metered into the indoor lower-pressure (evaporator) coil, which results in the cooling. The more efficiently and regularly the refrigerant is metered into the coil, the more efficient the system. Yet in past years, achieving the lowest-cost product in “builder model” air conditioners and heat pumps became the goal for almost all (if not all) HVAC manufacturers. The first thing to go was the high-priced TXV metering device (which ensures optimum filling of the evaporator), to be replaced by simple restriction devices which aren’t as efficient, but are much cheaper to manufacture.