Servicing your own air conditioning system to replace lost refrigerant is a good way to keep your auto repair costs down. The R-134A refrigerant in your late model Chevy is the replacement for the now banned R-12 (freon) refrigerant found in older cars and light trucks. R-134A is legal and available for the home mechanic to use and is substantially less expensive than R-12. With a set of A/C gauges, this project can be completed in an afternoon.
Attach the low-pressure hose to the service port located on the air conditioning system under the hood. The blue hose on the gauge set is the low-pressure hose, and the service port for this side of the system is located on the accumulator in most Chevy vehicles. The accumulator sits on the passenger side of the firewall. Refer to the service manual if you need help locating the port in your specific Chevy vehicle.
Connect the high-pressure hose to the high-pressure service port. The red hose is the high-pressure hose, and the service port for this side of the system is located on the small diameter, high-pressure line that connects the condenser to the evaporator on the fire wall. Refer to the service manual for help in locating this port in your specific Chevy vehicle.
Set the climate controls on the dash to "MAX" for the air conditioning and "MEDIUM" for the blower speed. Start the engine and allow it to run for a few minutes. This will stabilize the pressures on the gauge set and provide a more accurate pressure reading.
Screw the can of refrigerant into the can tap and connect the can tap to the yellow hose on the gauge set. Twist the thumbscrew on the tap clockwise until it stops then counterclock wise until it stops. This punctures the seal in the top of the can and opens it.
Open the blue (low-pressure) valve on the gauge set. Refrigerant will now flow from the can into the air conditioning system. When the can feels empty, close the blue valve and look at the pressures on the gauges. Stop adding refrigerant when the low-pressure gauge is 40 PSI and the high-pressure gauge is 350 PSI.
