Recharging the refrigerant on your vehicle's air conditioning system requires that you connect your R-134A recharge kit to the low side fitting near the compressor. With the air conditioning running, the refrigerant from the recharge kit is sucked into the compressor's storage system. However, if the compressor is not turning on, then you must troubleshoot the compressor itself before recharging the air conditioning. If the compressor cannot be turned on, then you must take the vehicle to a professional mechanic to have the system purged, replace the compressor and recharge the refrigerant.
Hook an OBD II scanner to your OBD II terminal on your car, which is typically located to the lower left part of the steering column behind a small panel. Turn on the OBD II scanner and turn on the car's ignition to the accessories position. Retrieve the OBD II code for any sensors or circuits that have malfunctioned or failed. If the air conditioning pressure sensor or switch comes up on the OBD II code, then you may need to replace it before the compressor will turn itself on. If your scanner does not tell you the interpretation of the code, you will need to look it up on websites such as OBD II Code or AutoZone.
Turn on your engine and air conditioning and listen for sounds such as metallic bearings clicking or loud knocking noises coming from the compressor. If you are hearing any of these sounds or have recently heard them, then your compressor is either lacking lubricant and refrigerant or has air that needs to be purged by a mechanic. If the compressor is low on lubricant and refrigerant, then you may be able to re-engage the clutch by using a jumper wire.
Locate the single wire connector near the front side of the air conditioning compressor. Unplug the single wire connector and hook it up to the jumper wire. Connect a jumper wire to the positive terminal of your car battery. Turn on the air conditioning system to full blast inside your car, which should cause the clutch to engage on the compressor.
Attach the recharge kit to the low side fitting, which is marked with an upper case "L," and turn on the recharge kit's valve. The low-side fitting is located between the compressor and the accumulator. Continue to allow the kit to recharge the vehicle's refrigerant until it is blowing out cold air again, measuring between 40 and 50 degrees Fahrenheit on a thermometer installed on your dashboard.
Watch the low pressure gauge on your recharge kit if it is included. The low pressure gauge should read between 25 and 40 psi (pounds per square inch) when the refrigerant is fully charged. To avoid the risk of overcharging your air conditioning system, which can cause expensive leaks, shut off the recharge kit when the low pressure reading reaches 25 psi.
