Oh he complained.
First time visit, he brought up that the downstairs would never really cool off. I started by looking at the filter, then went around the corner of that wall where the AHU is. I wanted to get a good look at the coil, so I thought I'd poke my head through the return instead of wrestling with the panel and that's when I got this surprise.
Because of the AHU's position, there's not a whole lot that can be done without moving it. The system is 20 years old, so I told him it'd be more cost effective to wait until the system needs replacing to retrofit the duct work and relocate the AHU.