Well my 98 chevy blazer LT has begun to not let the AC turn on until you drive it a mile or so, but it is inconsistent. I have personally replaced the compressor 3 times in the past 6 years and can tell it is fully charged by the cold suction lines when it is running. The dashboards climate control has a yellow light above the AC button that brings on the compressor and that light is not turning on when it should so this problem is computer controlled. One day it would flash when I pushed the AC button the next day no illumination at all for over 5 minutes of driving. I disconnected the low pressure switch and that of coarse turned off the compressor but the light stayed on which means that it is not related to my problem. I live in the middle of Texas and it only gets real cold here for a couple months a year and I can't remember what that AC light does on a freezing cold morning. I am suspicious of the inside temperature sensor is telling the computer it is very cold in the car and not letting the AC turn on. I don't know how to check this theory. I am guessing GM won't sell the thermistor by itself which is what usually goes out on most devices so maybe pulling the climate control apart finding the thermistor and splicing in a resister in it's place and see it the problem goes away but I would need to be able to find the thermistor circuit and guess at what ohms to stick in maybe 100 ohms. Any suggestions.
Thanks David French

 

If you have the automatic climate control, the interior temperature sensor is located above the driver door behind the small grill. This sensor can become clogged and not function properly. It is available separately.

 

Thanks Swartlkk for your help, It says on the front of the AC "Computer Climate Control", and there is a small vent above the fuse panel in the side of the dash but I opened it and didn't see anything in it. But it is very interesting to know that the temp sensor may be sold separately. Wish I could dig into more today but it will be over a wk before I get to this. David

 

Check out the link below:
Weird sound, weird speaker-like device on driver's side
There is a picture in there showing what I described above.