man it is hot where your at. I am not positive but I think it only cycles when it needs to. max a/c will make sure it stays on and won't cycle. but seeing that it is that hot there I don't see a problem with it staying on. the hotter it is the higher pessure you will have in the a/c system. I would turn the a/c on and leave the max a/c off when it cools down like around 60-65 outside if it will even get that cool and then see if it will cycle.

 

If you mean by static pressures that the clutch was disengaged, then the hi & lo pressures should be equal unless you just shut it off. I don't have the table in front of me but I think that at 90*, the static freon pressure for R12 is about 120 psi.

Another thing you need to do while checking is to have a large fan in front of the vehicle because you won't get good condensation especially at hi ambient temps which will cut down the efficiency. Try measuring the vent temps at 60 mph on Max A/C.

 

I did about a 10 mile trip today with the A/C in different senario's ie, Max a/c w/ blower at full, max a/c with blower at low and Max a/c at full w/ recirc and the temp with the front vent was at 52 degrees. I can see why temps might play a role in the a/c not wanting to cycle but in other vehicles down here they all cycle like they are suposed to and they all drip condensation from the acumulator. my max speed was about 55 when i ran these tests. Ill take readings one more time tommorow when i get a chance to see how the system is but im still confused. I know its a big vehicle but other trucks and Subs i have ridden in freeze your *** out of the vehicle when on full blast and this one just isnt doing that even though the A/C temp at the vent says 52degrees. the only guage i had for the low side was one of those cheap deals from autozone the high pressure was the real deal i have the real deal for the low side too but dont have the right fitting for it to work on the Burb. If you need an actual and not a ball park then ill get the fitting tommorow and go through it again to see if anything is different.

 

good advice about the 60 MPH ill try that tommorow as well. i didnt think about air flow across the condensor guess i thaught the radiator shroud would have that all covered.

 

OK well I tinted the front windows of the Burb the other day and the A/C is working a lot better. Vent temps still around 52* my wife says her side is cold after a few minutes and she has to close the vents but my side (driver) still isnt getting as cold as I would expect but nuntheless it is working great. Still havent found out why the compressor wont cycle, or no condensation on the acumulator but who knows maybee its just too hot here for that to happen. Thank you all for your help.

 

It's not unusual for the compressor to run continuously if the truck is just sitting in the driveway as it's not getting enuf air across the condenser to enable the low pressure to get low enuf.