1991 Honda Civic AC problems

I, m not sure what type of a/c sys tem this car has but the proper amount of freon is very important. To much canmake it not cool right just as to little. If you have the right amount of freon then it could be a couple of things. The heater control valve my be letting in some hot coolant to the heater core making the blower motor blow air across the hot heater core and then the a/c evaporator causing the air to be warm. The way to see if this is the problem is feel the coolant hoses going into the dash they should not be hot. Also check to see if the a/c compressor is running enough an not ycling on and off to much. It should not cycle very much at all sitting still with fan on high and it, s above 80. If it, s cycling to much it could be thermal control switch. If it is not cycling on and off to much and stiil not cooling put a set of gauges on system and if the low side is below 20 psi it is ether low on freon or bad expantion valve. Not to confuse you but one question, does the a/c seam cooler when you are driving? Because systems that have been converted don, t cool as well as they did with r-12 because the condensors where not designed for the higher pressures. But most work with pretty good cooling.