It is very difficult to answer this question specifically because you haven't indicated the model year of your brick. Nor whether or not its been converted over to R134a and how (through use of the Volvo kit or other means).

However, I suspect you have a system that has too much Freon in it. Did you attempt to charge the system without using a manifold (that the thing they put on it at autozone)? If you did then that explains why you're in the orange zone, which doesn't make much sense to me because there are two gauges on a manifold and one handles the high side (liquid) and the other the low side (gas). Okay, let cut to the chase when the system has too much Freon in it either by overcharging or a closed expansion valve on pre-1990 240s or a blocked orifice tube on later ones.

What you should do is take your car to a competent mechanic who is versed in auto air conditioning service. For about $150 they'll discharge, evaculate (remove all air and water from the system), and attempt to re-charge your car. If they're unsuccessful they'll troubleshoot the problem and determine if there is a leak (which is usually detectable after removing the old Freon and evaculating the system down to negative 30 psi) it will allow the vacuum out of the system (you won't be able to hold 30 psi pressure for 30 minutes) and then they'll put in a small amount of dye and freon to attempt to find the leak using UV light and a Halon detector. Most leaks are usually just o-rings that give out and are easily replaced at small cost. However, sometimes you may need major parts (eg evaporator, condenser, hose(s), accumulator or drier, compressor, etc., etc.). Its not easy repairing a/c systems, but having down my own on three differnt cars, including a 240 where almost everything was replaced, a dyi is possible provided you have requisite mechanical skills, have the proper tools, read the requisite number of books and manuals, talk with technicians about what they'd do and how you should proceed (your Volvo parts rep will be glad to get answers for you from the mechanics). However, most people don't have the time or aren't as crazy as I am so they find someone to do the job for them. Either a Volvo dealer, Volvo Repair Specialist, Foreign Car Repair Show, or an ASE certified all-around repair shop or service station. Do yourself a favor and stay out of Autozone...they mean well, but they can get you into some real hurt at times.