Stupid charged 2013 Volt's A/C, overcharged, car shook and a little smoke/smell came

Of course immediately turned off A/C after a few minutes and mechanic drained it and charged to appropriate pressure. Everything's working fine running A/C for 2 hours --- but warning to others. Those cheap ($40) charge kits from Pep boys have unreliable pressure sensors or something.

If anyone knows what the temporary smoke/smell was let me know. I read in other forums that overcharged air conditioners always shake the car.