How to Add Freon to a Dodge RAM 2500by Jack Hathcoat
Although the Dodge Ram has changed a great deal over the years, the A/C system has essentially remained the same--other than minor changes to use the new 134-A refrigerant, and more efficient compressors. This also means that servicing the Dodge Ram 2500 system hasn't changed much over the years either. Just follow a few, routine steps, and you too can service your A/C system.
Raise the hood of the car. Bolted to the back of the air conditioner compressor are two hoses. One hose is larger and goes to the firewall at the back of the engine bay. This location on the firewall is where refrigerant enters and leaves the truck cabin. The suction hose (the large hose) pulls the refrigerant from inside the truck cab where it has circulated and extracted the heat inside the truck. The smaller hose leaving the back of the compressor is routed to the front of the truck. This is the discharge hose that carries the hot refrigerant to the condenser that is located in front of the radiator where it dissipates the heat that is captured in the R-134A refrigerant.
Remove the service port caps that are located either on the hoses or compressor, depending on the year of the Ram 2500. These ports are labeled if they are on the compressor by the letters S and D. S stands for suction and D for discharge. Close the service valves on the A/C service gauges and install the hose that is connected to the blue gauge onto the S port. Connect the hose that goes to the red gauge onto the D port. Install a can of freon onto the can tap that is connected to the center hose of the manifold gauge.
Start the truck, turn on the A/C and read the A/C service gauges. It is not necessary to open the gauge valves. If the A/C gauge readings are zero, the 134-A refrigerant has all leaked out and there is no refrigerant pressure inside of the A/C system to read. Repairs are needed before recharging, because all of the refrigerant would leak out again.
Add a can of refrigerant if the A/C gauge pressures are rising and falling as the compressor is turning on and off. This means there is not enough refrigerant to keep the compressor electrical system energized, so pierce the can of refrigerant with the can tap that is part of the A/C gauge service set, and slowly open the A/C gauge blue valve allowing refrigerant to flow from the can into the A/C unit.
Turn the blue valve off and allow the system to stabilize. The pressure readings need to be around 35-psi and 250-psi, but there are variables involved. If the day is very hot and humid, the low pressure (blue gauge) may read upwards of 40-psi or more, and the high pressure (red gauge) could reach 275-psi. Add refrigerant until the desired readings are achieved and shut off the valves, then remove the hoses. Replace the service port caps.