Anyone have the right numbers for pressure at different temps for our trucks?

 

It all depends on the temp and if your fan is being engaged when the engine is warm. Since our trucks use orifice tube to drop the pressures they will be a little higher than normal. Should be from 32 psi to 40psi depending if the fan is running and what the outside temp is. You also have to watch the high side pressures. They should be between 250 to 350 psi.

 

I checked the pressure yesterday afternoon. It was after a 30 mi drive with the AC on the whole way. Outside temps were around 111. Low side was at 30 psi, I gave it one can and it bumped up to 45. AC was blowing colder, but seems to take longer to get cold after shutting down and taking off again a few hours later. I did screw up and leave the can upside down for a moment so it may have some liquid in the low side.

 

Within a few minutes, any liquid in the low side would have evaporated.

Mine was really low on Freon. It would only get to about 50F on 100F days. Low side was 20-40psi, high side was ~230-273, depending on clutch cycle and ambient temp. I added about 1.5 cans and now I get 40F or lower out of the middle vent and at 100-110F, pressures are about 20-40psi low side, and 275-290 high side.

Tony

 

Im going to check the pressure again and make another evaluation after driving. I noticed right off the bat that I had cooling on the passenger side again where I did not before. What is the MAX low side PSI I should look for? My gauge turns red at 55.

 

Your low side should only be 30-35, 45 is too high. Your high side is twice the ambient temperature. If humidity is greater than 50%, then add 10 degrees for every 10% humidity above 50%
Be sure to run the AC or drive for at least 10mins at max cold on max fan prior to taking your pressure readings.

 

just remember your pressures and temps are going to change at idle and while driving, the fan dosnt pull enough hot air off the condensor for it to work great

30-35 low
225-250 high (depending on outside temp)

remember over charging will make it warmer just like undercharging

having it recovered and recharged by a machine like we have at the shop is the only 100% way to know its got the right level in it, shouldnt cost too much