So I turned my A/C on (for the first time). I was getting coil freezing (evap). I knew because when I took the cover off from the unit the entire coil was a block of ice. I defrosted it and checked for the stupid things (bad filter, closed vents, restricted return). I tried again and the coil froze up again. I called the same company that did work on the system last year, where they replaced the entire compressor (previous home owner). He put his gauges on it, indicated it was low. I showed him the receipt for the work done last year in June. He indicates on the receipt he vacuumed the system down to 183 Microns and that if it was leaking at that time that they should have caught it. He also indicated that I should not have lost this much refrigerant in a year period. He put in 2 lbs and the system started working again.
He took the cover off from the unit and found the evaporator coil was rusted up, he indicated that the leak is likely coming from the evap coil and it needs to be replaced (he did no leak test). He said if he can find the coil it's going to be about $1400. My question is why didn't he do a leak down test, and also is it possible that they system was never charged properly?