How to service 2005 Highlander A/C with gas.
If you are asking how to recharge your AC system, take it to a qualified AC shop. AC systems are not for do it yourself regardless that refrigerant is sold in stores.
Pay to have it done right rather than risking injury to yourself or causing further damage to the system.
@Purebred Agree! A competent A/C shop is often better equipped and qualified than the selling dealer and less expensive. We deal with a firm called Auto-Temp who specialize in heating and A?C service.
I would not attempt to do any work myself.