In Canada our winters get real cold minus 30 celcius and things contract, small amounts of refrigerant leak out past shrader valve and plastic cap. BUT if you use lock tite (discuss with expert central and at the factory) you should have no escape during winter. Just so you know we do leak test every systems and leave unit until summer before charging. when we get back in summer we have found unit to be low on refrigerant 2 or 3 lbs low and on many units. Yes we do A/C all year round with complete packages.