How to Charge a 2004 GMC AC

by Richard Ristow

A 2004 GMC vehicle's air conditioner will eventually run out of refrigerant; one day, you will turn on your air conditioner and find only warm air coming out. But you shouldn't be overly concerned. You can easily find an R134a Freon recharging kit at most automotive retailers, and you can recharge the refrigerant quickly at home. Think about getting this done before the most hot summer months begin.

Step 1

Put on protective safety equipment. Open your GMC's hood. You are looking for aluminum pipes. They will be similarly located in most GMC models. Look toward the center of the engine, and you will find a thinner and a thicker pipe. The thicker one is the low pressure line. On it, you will find the low end pressure outlet. Take the cap off this outlet.

Step 2

Connect your R134a Freon kit's service hose to the low end pressure outlet. Set the kit down, but make sure you leave it in a spot that does not feature belts or other shifting engine parts.

Step 3

Start the GMC's engine and let it warm up. Activate the air conditioner at its coldest level. Turn the air-blower to its highest setting.

Step 4

Walk in a circle around your GMC automobile. Open all the doors and make sure the air conditioner does not de-activate itself.

Step 5

Turn down the valve on the R134a Freon recharging kit. By turning it "down" you will be turning the valve towards the canister's seal. The valve contains a stem that will puncture the R134a canister's seal. Let 60 seconds worth of R134a Freon refrigerant rush into the system. Then turn the kit's valve upwards and away from the canister's seal. Let the air conditioner's blower circulate the new R134a Freon for 60 seconds.

Step 6

Monitor the air conditioner's internal temperature. Stick a thermometer into the GMC's central air duct. Once your thermometer detects 40 degrees, the recharging process is over. When set to its coldest temperature, a fully operational air conditioner chills air to 40 degrees. Under the influence of extremely hot summer weather, the reading could end anywhere between 40 and 60 degrees. You will know the process is complete when the temperature inside the air conditioner system stops falling and becomes consistent. Since the system is pressurized, be careful to not overfill the system. Use your kit's pressure gauge as a guide.

Step 7

Remove the thermometer from the duct. Undo the connection between the kit and the low side pressure connection. Let the GMC sit for another 10 minutes, ensuring an even distribution of freon. At the end of the process, turn off the engine and the air conditioner. Close the hood and all the GMC's doors.

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