Buyers must prioritize Cooling Capacity (BTU), typically ranging from 12,000 to 22,000 BTU for passenger vehicles. Ensure the unit features a high-quality copper evaporator coil for superior heat exchange and durability compared to aluminum. Additionally, verify the Airflow Volume (CFM); a professional-grade unit should provide at least 350-450 CFM to ensure rapid cabin cooling. Check for multi-speed blower motors (usually 3-speed) and adjustable thermostats to provide end-users with precise climate control.