I am purchasing this car from the second owner. The car has around 75,000 miles on it. What should I look for? This is my first Volvo, but not my first turbocharged car. Thanks for the help.

pull the pollen filter under the passenger side firewall and see what kind of accumulation of crap is sitting on the A/C. I have seen several late 90s with significant rot from crud in there. Repairs can get up to $1-2K.
Have they used synthetic oil? pull and examine/sniff the tranny dipstick.

Thanks, is this how the evaporator problem begins? From the crud?

Take it to a reputable mech, and have it looked at. For the $75 to $100, it's worth it.

97 is a good model year on the 850's. check maintenance records. also see if timing belt's been changed. check a/c if working. check if trac/abs lights are on or off.
good luck

Would I check the lights for operation? Or to see the owners driving style? Thanks