If the air conditioning system in your Jeep Cherokee seems not to be cooling as much as it once did, there's a good chance that the refrigerant is low. Modern systems like these use the environmentally friendly refrigerant known as R134a, which is available by the can in auto parts stores. The procedure for adding R134a to the system is much the same in every vehicle, and learning to do it yourself can save you some time and money.
Put on your safety glasses, and screw the kit onto a can of refrigerant, first making sure that the rubber seal inside the threaded portion of the kit is securely in place.
Remove the protective cap from the low-pressure charging port, which sits on the large low-pressure line between the compressor and the evaporator, and attach the quick-connect fitting to the kit's hose. On a 1996 Cherokee, the port can be found right by the plastic coolant recovery tank.
Turn on the air conditioner, and allow the engine to warm up. Remember to keep the charging hose away from any moving parts.
Pierce the can open by turning the valve handle on the kit, then back it out again to allow the refrigerant to pass through. If the compressor cycles off, remove the connector from the accumulator, and hook up a jumper wire with alligator clips between the terminals to keep it engaged.
Add refrigerant until both the surface of the accumulator and the inlet pipe from the evaporator feel about the same temperature. The accumulator is a metal canister located on the passenger side of the Cherokee, near the fender-well and also on the low-side line. Its inlet pipe is the section of the low-side line that goes into it from the evaporator, behind the dash. A thermometer may be placed in the center duct of the vehicle to measure air temperature. A fully charged system should cool to about 40 degrees Fahrenheit or generally 30 to 50 degrees cooler than the ambient air, depending on the outside temperature and relative humidity. Some charging kits also come with a low-pressure gauge attached that can be used to determine when the system is fully charged.
Repeat the process with an additional can, if necessary. Close the valve handle when the can is empty, and disconnect from the low-pressure port. Replace the protective cap on the port, and save the charging kit for future use.
