Hi, Im greatly considering a 1986 190d, 250k miles, for $2500. The A/C does not work. The fan works, but not the a/c. The owner doesn't know what's wrong with it.

My question is: Is there a simple diagnostic I can run if I purchase the car? And if I do find what is wrong with it, is the A/C system easy to access and replace? I have little to none car mechanic experience, but I'm very handy and i have the owner & service manual.

A/C is nessecarily for me as I would be driving the car down to Arizona when i move there in the summer
Thank you!
Torin