AC freon leak question
I recently found that my home AC system had little or no freon. I foolishly did not have the level of freon checked for the last 3-4 years. Today, I had the system recharged with 8 lbs of freon. During the fill, the technician visually observed the unit for signs of an obvious leak, while also monitoring the stability of the newly added freon. He detected no obvious leaks, either visually, or from some unexpected instability in equipment monitored freon levels during or immediately after the fill. I know that freon is order-less. Still I do sense a bit of a smell, which I assume to be dirty coils from years of condensation buildup. This peculiar smell, though quite light, has been around for several months...say 5-6 or so. In the end, I feel that given the time in which I had not checked the freon levels (3-4 years), that more than likely the system has a very, very tiny leak where it loses a tiny amount of freon daily until it finally bled dry some 4 year later. Due to the likelihood of this theory, I elected to NOT have a freon halogen leak test...a savings of $150....and instead simply filled the system. I would appreciate any thoughts you might have about my reasoning on this matter and the course of action I selected. Thanks for any help you might provide.