Thread: Any A/C experts out there?

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Stu Cool,

I agree with DennyW. Your high side is too high. I would make sure the system is not overcharged. I am no expert but I am fortunate to be friends with one. I also own a telecommunications company and one of our clients in Dallas is the Sanden manufacturing plant located in Wylie. So I am lucky to be able to ask some of the engineers about the 508 unit in my sedan.

And like the issues you are describing, I too am having similar issues which occured just after I put my engine back together and had the system recharged.

When I called one of my buddies, he told me it sounded like overcharging was the culprit. He stated one of the most common mistakes with aftermarket systems is overcharging. He continued to say that overcharging is usually caused by filling the system by watching the gauges instead of simply filling by the correct measured amount of freon. For example, my Vintage Air system only takes 1.8 pounds of 134a refrigerant. He said any more than that will cause the low/high pressures to be high. He stated the low side should be around 6-12. This may seem extremely low, but he said these systems are very different than stock systems and run a much smaller low side pressure. And the high side should be no more than 2*ambient temp + 20%. So in texas with the current temp around 100, the high side should be no more than 220. Make sense?

When I had the system charged by the local shop (I know...I know what your thinking...but I was in a hurry to make a rod run and took the easy way out instead of doing it myself...another lesson learned!), I noticed a loud "screeching" sound when the engine was revved up. This turned out to be the high pressure switch cutting off the compressor and then allowing it to cycle back on as soon as the pressure lowered. This continued to happen until we drained the system of refrigerant.

It now works, but not as well as it did before when it was charged correctly. So this weekend I plan to vacuum the system down and start over. This time I will charge only the correct amount and I expect the problems to be solved.

Again, I am no expert, but I trust my friend and he knows his stuff! I will let you know how it turns out.