Good work and follow through Andy. If refrigerant was low there must be a leak somewhere so pay attention to it for a while. Mine got low after I changed out a damaged radiator and I left the condenser coil hanging for a few days while I sourced the part. I suspect this stressed the connector o-rings but once bolted back in place the leak stopped. Like you my mix flaps were A-ok but I have seen a bunch that weren't.
The process of elimination works.
