I had taken my Tacoma in to
I had taken my Tacoma in to my mechanic (not Toyota) to replace the alternator which had seized in place. When I got the vehicle back, the A/C didn't work and I was semi-convinced it was something he did. I took it back and he checked the pressure of the coolant gas in the system and found it empty. He refilled for about $50 labour and I was on my way. Your dealer said it "may" need a compressor, but he should check first for gas content. My mechanic said the seals on these things can leak gas if the units are used frequently.