Quick question - Low too low, high too high

I have a 3 ton american standard on MO99 that's getting pretty old. It has a fairly slow leak and I checked it this afternoon to see how it looked heading into winter. I have to charge it every spring, usually around 3lbs. It was about 70 degrees outside when i checked it today. The low side was around 60, which i didn't think was too bad. But the high side was around 220 and the pt chart says i needed to be around 180. I guess i way overcharged it last time? Any thoughts on another reason why the high side was a little high, but the low side was close? Is there a way to let some pressure out of the high side, but not make low side drop even more? I appreciate any help you can give. Feel free to answer me like I'm 5. I'm obviously new to this, just trying to limp an old system to the end.

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