96 Dodge Dakota Air Conditioning

Is the air coming out of the vents cold? It may be normal cycling as compressors are not supposed to run continuously.

Only one of the lines going into the firewall in the engine compartment should be cold (low side), other should be neutral to hot (high side).

No cold air is coming out and yes, it is only the low side that is cold. I spoke to a friend at work who told me that the refrigerant may be low. There is a recharge kit that has a pressure gauge so I can tell what the charge is. I just do not want to charge the system if I have to replace the compressor.

Sounds like it's not building up much pressure, which may be why you are not feeling cold air and why it keeps cycling.

It may have a timer built into the system that limits the compressor's ON time to 5 seconds with a minimum of 20 seconds OFF time.

One thing you need to check is that the air conditioning system's doors are opening and closing correctly to direct air from the condensor into the cabin of the vehicle. If you look under the dash on the passenger side, you should be able to see the levers attached to the internal doors in the ductwork. Watch those levers and see if they move when switching from heat to cool to outside air and recycling inside air.

If the doors are working, you will need to get a mechanic to check the high and low side pressure in the system while it's running. This is something that an amateur should NOT do on their own. The pressures involved are DANGEROUS.