The 2nd Gen LS has no cold air bypass door. Even if it did, it would not cause your symptom. The service manual says to ignore B1265 because the LS is not equipped with a cold air bypass door. Don't believe me? Pull the DATC out and look at the pins for the CAB actuator. There aren't even any wires attached.
If you are getting hot (heated air) out, then it is indeed the DCCV. If so, you will get cold air out on the first startup of the day, before the engine warms up at all. If, instead, the air just isn't very well cooled, then it is probably low refrigerant. Don't use that Artic Freeze crap. Real R134a is already synthetic. Everything in the Artic Freeze can that isn't pure R134a reduces the cooling capacity of the system. To correctly charge it, you need to monitor both the high and low side pressures and compare them to the temperature charts. If you don't have the tools to do this, get it done by someone who does.