1. Too MUCH coolant will not cause metal on metal noise
2. Too MUCH coolant(hi side to much pressure) can cause the belt to slip on the pulley and cause a rubber screech noise .
3. You do NOT look at the low side pressure when filling a system. You want the HI side pressure which is a better indicator. You look at the Low side as a "help" to get the complete picture when charging.
4. I HOPE that you made an error when you said Freon Leak charge--you meant 134a leak charge. Doug
PS. AS everyone knows, the EPA has thousands of enforcers traveling the country looking for people that vent Freon 12/134a in to the atmosphere. They watch websites such as this and will make a visit once someone posts they vented to the atmosphere:W