How to Recharge a 1999 Silverado AC System

by Lee Sallings
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Recharging the air conditioning system on your Chevy Silverado is necessary after you perform repairs that involve replacing parts. The 1999 Chevy Silverado comes equipped with an R134a system that can be serviced by the home mechanic with average skills and experience. This repair project does require the use of a vacuum pump and an A/C gauge set, which are specialized tools that are available at your local auto parts supplier and may be available for rent.

Step 1

Attach the A/C gauge set to the high and low pressure service ports located on the A/C line near the passenger's side rear firewall. The ports are sized so that the gauge set cannot be installed improperly. Twist the knobs on the hose ends counter-clockwise to make sure they are released, and pull the quick disconnect ring to snap them into place on the service valves.

Step 2

Attach the vacuum pump to the yellow service hose on the gauge set. Plug the pump into an electrical outlet and turn it on. Open both valves (red and blue knobs) on the gauge set, and allow the vacuum pump to pull vacuum for one hour. This insures that all moisture has been removed from the system.

Step 3

Close the service valves on the gauge set and turn the vacuum pump off. Remove the pump from the yellow service hose, and attach the can tap in its place. Snap a can of refrigerant into the can tap and close the lock on the tap. Turn the thumbscrew on the tap all the way in, and then all the way out to open the can. Start the engine, and set the A/C dash controls to maximum cooling and medium blower speed. Open the low side ( blue knob) service valve on the gauge set and allow the refrigerant to flow into the system. The A/C system on the Silverado holds 2.5 lbs. of refrigerant. Each can is 12 oz. so the system holds just under three cans of refrigerant. When the first can is empty, close the blue service valve and add the remaining cans to the system.

Step 4

Turn off the engine and allow the pressures displayed on the gauges to stabilize. Turn the knobs, on the hoses attached to the vehicles service valves, counter-clockwise and pull up on the quick release ring to release the hoses from the vehicle. Test drive the truck to verify the repairs.

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