How do recharge rear ac 1993 gmc?

To recharge the rear air conditioning on a 1993 GMC, first locate the low-pressure service port on the rear AC system, usually found near the evaporator. Ensure the engine is running and the AC is set to maximum. Attach a refrigerant can to the port, following the manufacturer's instructions, and slowly add refrigerant while monitoring the pressure gauge. Be cautious not to overcharge, and check for any leaks in the system afterward.