I have a 2008 Cadillac DTS. The A/C is blowing hot air, but the freon pressure is good. Is there a switch/sensor that may need checking/replacing? I work in a dusty environment, and a couple of months ago, I tried to get the cabin filters replaced, but the garage was unable to get a replacement. Is there any connection to the cabin air filter being dirty?

NO, the cabin air filter is not causing the problem you are having, it might cause low air flow into the cabin but it can not cause the system not to cool, how do you know the pressure is ok? did you install a set of gauges? also this car is equiped with a climet control computer, and should have a trobble code if the system is not working. have someone like autozone retreve the codes and get back with me and i will look them up and see if i can help you get to the bottom of this problem. you might try having autozone clear the codes after retreving them that might be all you need done to reset the computer.