Upflow install with a Goodman modular blower with 20kw heat package, and a cased coil...
I was out for no cooling, but found out from the customer that they kept having to reset the HPS on cold days in the winter. It's pretty obvious why, lol.
In addition to the blower and coil sections being in the wrong order, the coil had at least one refrigerant leak, and had lost the entire 17 pound R-410A refrigerant charge.
This was a homeowner DIY install of internet purchased equipment, with help from a "friend that does refrigeration work for a beverage company".
According to the wife, the husband did all kinds of research before installing it.
I quoted them a price for reinstalling it correctly, with a new coil.
The total for what I quoted + what they already spent buying the equipment retail on the internet comes up to more than I would have charged them to correctly install a new system from the start.
They were not happy with me when I told them their coil had no warranty coverage, so I doubt I'll hear back from them.
Not that I want to hear back from them...