A technician is checking the charge on a system equipped with a thermostatic expansion valve (TXV). Which measurement is the preferred way to verify the charge on a TXV system?

Explanation

On a TXV system, subcooling is the preferred method to check the charge because the valve maintains evaporator superheat fairly constant. Subcooling is the difference between the liquid-line saturation temperature and the actual liquid temperature. Superheat is the main check on fixed-orifice systems rather than TXV systems.