72 A/c Air Conditioning Troubleshooting

[kna4977]

I have my factory system installed and charged. The problem is it doesn't blow as cold as I think it should. The compressor runs all the time when the control is set for A/C, not sure if it is supposed to or not. The POA valve and hoses are frosty/icy with the system engaged with a lot of condensation due to engine heat when the system is turned off. The center outlet has colder air than the side vents. The water valve seems to always let water through, except on the rare occasion that I can increase vacuum to it by placing the truck in park and ideling at about 2000 rpm. In drive, under load, it has virtually no vacuum until I let off and coast which allows the air to be somewhat cooler, but not cool enough. The lack of vacuum at the water valve I believe is most likely causing heat to mix with the cool air, but like I said before as vacuum increases, the air does get colder, but still not as cold as it should be. Also, is there a way to increase vacuum on a consistent basis so that there is always enough to close the water valve? I did try to bypass the water valve to see if it the A/C was colder that way, but the truck wants to overheat. Any tips you can give me would be great!