Well yesterday i thought i repaired my A/C in the Mack. What i did was:  Research  "you tube" on putting freon in . Wow that was easy , you just buy a can of 134A freon, a 10 dollar hose gauge kit and install new pressure. My A/C worked great! for a half day. Then on my 200 mile drive in 90 degree weather it leaked out.. Any one know of where the usual leaks are on a Mack? Does that stop leak freon work? or will it clog up the system and cause damage. I guess the next step is to inject color and look for a leak. Any good tips?

I just bought a fan and mounted it on the roof center.

first thing is to check the schraeder valves,basically a tire valve stem,the low pressure side and high pressure side have different size fittings.Here in south Louisiana it does get a little warm so an AC repair man can be a definite asset.I am not a repair man but have watched and noticed they used 2 gauges,1 on high pressure side 1 on low pressure side.There should be information somewhere telling you the exact amount of freon to add to an empty system.But there is a definite balancing act between high pressure and low,and the amount of oil added.

It was amazing how easy it was to put freon in. just start the engine a/c on high and plug in the hose with gauge on it (you can buy one for 10 bucks). Screw a can of freon on it. Yeah the valve steam may be leaking? I think i might try a bubble test with soap. This time of year A/C is a must.Even in Northern MN..