You might.. be able to sleuth out locale of a pressure switch mounted on the freon line, at some place near heat exchanger (the warmer input side, where the line will have vapor, not icy liquid.) If in luck - the circuit diagram should be under a cover somewhere?

You could then, when confident that IS what you found: pull its connector and make the obvious deductions: need to see it it's a NO (Normally Open) or NC (-closed) and decide if you want to temporarily bugger it: if compressor then starts - it's all likely about just low freon.

(While the lube oil should not be missing necessarily, via the leak - it might be, so you want motor OFF real soon, next.)

So then - you'd need a leak test, presumably a careful vac. test after that's supposedly fixed: before wasting a new charge that might disappear in some days. You might be able to bargain better, if you get this far, eh (?)

Luck
(I don't Evah want to see the inside near my car's heat exchanger! the Entire Dash would have to come out. Houses.. so much simpler.)