How to Charge an AC Compressor on an Astro


The Chevrolet Astro minivan was manufactured with optional air-conditioning, which uses a pressurized freon coolant system to lower the cabin temperature. Some later models were equipped with rear A/C, which uses ducting to force cooled air to the rear of the van, but uses the same compressor as the front-only models. Recharging the system will take the average backyard mechanic about 30 minutes, but the underlying cause of the leak should be determined as soon as possible.

Things You'll Need

  • Can of 134a Freon
  • Can of 134a mixed lubricant
  • Can of ultraviolet dye
  • A/C recharge valve kit
  • Connect the can of freon to the valve kit by pushing the top of the can into the bottom receiver of the valve and turning the can clockwise. The threads inside the valve adapter will draw the can into a needle that will puncture the top of the can and pressurize the valve. If the valve is equipped with a pressure gauge, it should now show positive pressure.

  • Connect the nozzle hose of the valve kit to the low pressure side of the air-conditioning system by pulling the outer ring back on the nozzle tip, pressing the tip against the low pressure nipple, then releasing the ring so that it catches the nipple and locks shut. Give a slight tug to make sure the connection is solid. The low pressure nipple is on the line between the compressor and evaporator, and should be colored blue on 4.3 V-6 models.

  • Start the Astro's engine and set the air-conditioning to the maximum setting. Release the valve either by turning it counterclockwise manually, or pulling the trigger. The can of coolant will become cold, and it will discharge into the vacuum of the low pressure line. Do not turn or shake the can, but stand it upright and allow it to drain in about five to six minutes. Close the valve, and turn off the engine.

  • Turn the can of spent coolant counterclockwise from the valve adapter and discard it. Insert the can of lubricant into the valve and turn it clockwise until it pressurizes. Repeat the procedure of discharging the lubricant by cranking the engine, setting the A/C, opening the valve, etc. The lubricant is crucial for the proper operation of the compressor, and one small can should be added for every two cans (about two pounds) of freon. The Astro can hold up to four pounds, depending on the model.

  • Repeat the procedure for charging the system for adding the UV dye, to detect the leaks in the gaskets and seals. To continue to add coolant to a leaking system can become expensive, and the system could be damaged by a low coolant situation.

Tips & Warnings

  • The system will typically only take in as much freon/lubricant as it needs. The vacuum will draw from the can at a slower rate until it is barely drawing at all.
  • Use extreme caution when working with freon. It can freeze the skin in very little time.

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  • Photo Credit Justin Sullivan/Getty Images News/Getty Images
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