Inside heat pump evaporator coils freezing up. Tech came out said unit low on refrigerant and added 1 1/2 pounds. Worked a day and a half started freezing up again. Called same company, same tech came out did somewhat of a leak test. Checked the inside evaporator coils, no indication of leak with the electronic tester or soap bubbles. Checked outside condensing unit same methods, assumed it was somewhere inside the sealed coil unit, recommended replacing outdoor unit. His electronic sniffer never went off, I was there. No visible oil residues. Talked to office trying to give me a quote on unit, told him not satisfied leak was pinpointed. Said he would send out another tech. This guy came, said outside not leaking, but when he had the electronic sniffer around the Schrader valves it went off. He said some leakage there was normal. Then checked my inside evaporator coils and said it is a coil behind the tin. Recommends a new evaporator coil unit inside.
Unit is 11 years old. Only problem before now was capacitor when under warranty when a couple years old.
Questions are? Is leakage around Schrader valve "normal"? after reading some online, I've learned now after the fact, they should have done a leak test and never added the freon until leak was repaired. Any advice would be appreciated.