I'd pass on it. Depending on where you are, A/C repairs can
be huge. I'm in Texas and can't survive the summers without
it.

The mismatched tires bugs me as does the tape over the
check engine light and the tranny leak. It sounds like the guy
only takes it in when there's a problem rather than getting
regular maintenance.

You said the guy has a stack of maintenance slips. I'd read
those carefully. Look to see if all recommended repairs were
made, it's usually noted on the slips.

Bill