I suppose $$ are an issue - can understand that, but where's the value(TIME and $$) changing out a unit every 2 yrs. that might last 10 or more using a real compressor?

I went through this years ago with Auto Zone. $39 alternator for a 1980 Dodge Diplomat. Failed every 3-6 months. No problem. Pull it off and take it back - get a new one. 3-6 months later, same deal. After about 4 or 5(lost track), I broke down and paid about $100 for a real one. Never changed it again.

Receiver-Drier - any time you open the system, change it. Just my 2 cents.