How to Recharge Your Car's A/C in 15 Minutes

Get your car's air conditioning in shape for summer and beat the heat with these easy steps.

By: Dylan Eastman

Has your car's A/C system lost its cool? Refrigerant can leak slowly from your car's air conditioning system over time, but recharging the system so it once again blows cold air is an easy DIY task and takes just about 15 minutes.

Tools + Materials

  • PSI pressure gauge
  • UV kit (optional)
  • car A/C charge kit with proper refrigerant for your vehicle

The first thing you'll need to do is purchase a charge kit for your car. Consult your local auto parts store for the appropriate type of refrigerant. The common off-the-shelf refrigerant is R-134, which became mandatory in the 1995 model year as R-12 was phased out due to its ozone depleting characteristics. If you have a vehicle made between 1992-1995, you may have either R-12 or R-134. If your vehicle does have R-12, it has to be converted to use R-134, which is a job best left to an A/C mechanic to handle.

You may need more than one can of refrigerant; I needed two to charge my system. The cost for the complete kits range from about $30 per can to about $55 for a kit with two cans. Look for a kit with UV dye, as that will help you track down any minor leaks in your system.

Find the Low Side Port

Next, find the low side port of your A/C system. This will be the barb on the larger tube between the compressor (mounted to the engine and with a belt) and the evaporator (a large aluminum can). If in doubt, consult your service manual or local parts store.

Attach Can of Refrigerant

Screw the dispenser hose and gauge onto the can of refrigerant. Attach to the low side port by pulling back the outer slip ring, pushing it on and releasing the ring. Next, start the engine, turn the A/C system on max and check the gauge reading. The compressor clutch should be engaged and the front of the compressor spinning. If the pressure is lower than 20 psi and the compressor is not engaged, then dispense refrigerant until the clutch engages. Be sure to shake the can first and every 3-4 seconds later.

Continue Dispensing Refrigerant

Consult the pressure chart in the refrigerant instructions for the proper system pressure. Continue dispensing refrigerant and rechecking the pressure until the desired level is reached. In my case, with an ambient temperature of 85 degrees, the instructions called for 45-55 psi. Be sure not to over-pressurize the system. If you feel like the can is empty, flip it over to dispense the remaining oil before removing.

Check for Minor Leaks

If you bought UV dye as part of the kit, check the system for minor leaks so repairs can be made if necessary. Use the UV pen and examine all valves and junction points in the system. In my case, I found a small spot where the front A/C feeds refrigerant to the rear A/C under the car.

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