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To check the refrigerant charge you need a set of gauges or a service station that can weigh the refrigerant that is taken out of the system. The high side service port is located in the passenger front of the engine compartment on the receiver/drier and the low side service port is underneath the driver side on the a/c compressor.
ASE Certified Technician
12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes