Volvo Repair: Air Conditioning Troubleshooting, volvo wagon, proper diagnosis

Question
I've been driving my "new" 1988 volvo wagon (my first car) for 2 weeks now and am suddenly experiencing problems with the air conditioning- Ie I get outside temperature air (which is very hot where I am) instead of cool air. Can you suggest some basic things to check before I have to conclude that something major is wrong?
The car went through a 44-point inspection before it was bought and has had a major tune up. Is it possible I am leaking refrigerant (I haven't  noticed this though)? What Fluid levels should I check>?

Thanks so much!

Answer
the 240 air conditioner system was not all that great to begin with.they do not cool all that well.there could be a leak somewhere.if it has a leak I would fix the leak and replace the reciever drier this is the filter for the system and the expansion valve.the car will need to be looked at for a proper diagnosis.the pressure of the system will need to be check first then fault traced form there.