Haulin_in_Dixie

Yes, 20 is not enough to cool it. Fill it until the cycling slows down to 30 seconds or more.

2 busy

Ok , i see there are a couple of different problems here. I have not done much work on auto a/c systems but the same principles apply.I worked on residential and light commercial.

First there are a few things that can couse low cooling. 1. dirty evaporator 2. restriction in line. if there is a restriction in suction side(low) it will increase high side readings. 3. low freon that will give low readings on both side and will couse freezing the evap. which is really freezing the moisture that usually drips out under the truck. 4 moisture in system, which if it has been working for years without any problems there probably should not be any moisture unless a major component has been changed. usually there is enough residule freon in the system to keep a slight positive pressure keeping any moisture from entering


To charge a system the compressor has to be running, have some one inside the cab accelerate throttle, you will see the pressure drop on your gauge. you will not get enough freon in the system to cool it if you do not idle it up . remember driving down the road the compressor is spinning faster than at an idle.

ctdnut,
your problem may be the thermostat not seeing temperature . i'm not sure where it is on these trucks. have not had the need to look for it.

there were so many post on this topic i'll have to go back and read them to see what i may have missed.

newriverSpecon

2 busy is right about having someone bring the RPM up. Here in AZ the condensor can not cool enough at idle. This is VERY criticle with 134. We have had times that we put box fans in front of the condensor and mist some water form a hose to get it pull enough heat out. And this was in the shade. If you get desprate I can recommend someone in downtown PHX.

Randy