Customer called stating AC froze up two nights ago. Arrived and assessed system, refrigerant charge appeared to be low. Verified proper blower speeds, found that blower was not calibrated to size of AC equipment. Calibrated blower to proper CFM for equipment and rechecked refrigerant. Charge was still low so a leak search was performed with micro bubbles. Found that suction service port schrader core was bleeding pressure after system turned off and would leak until pressure in line dropped to a point it would hold, I suspect it’s been doing this since install. Replaced schrader core in both service ports, vacuumed system and set charge to manufacturer specifications. Monitored system operating for 20-30 minutes to ensure pressures were good and metering device was operating properly, charge is good.