Need help.... I have a 04 ranger xlt 4.0 4x4. My a.c. blows cold but my compressor wants to click on and off every 5 to 10 seconds. I checked the low side pressure and it climbs to 50 psi and then drops to 20 then back again which takes about 5 to 10 seconds. Any suggestions????

 

The A/C cycling like that is a typical indicator of a low Freon charge. Another possibility is a faulty cycling switch or other sensors.

 

Chart here on what pressure you should see at what OUTSIDE temperature: AC Pressure Chart | R-134a Temperature Pressure Chart

Thats a pretty big swing in pressure

Compressor needs oil or it will burn out, the oil it needs is in the refrigerant, the Low pressure side is the refrigerant flowing INTO the compressor, so if it drops too low the switch opens and compressor shuts off to prevent it "burning out"

Why it drops low can be a few things, not enough refrigerant in the system, or a blockage that is limiting the flow thru expansion valve or accumulator/dryer

High pressure side switch prevents fittings/hoses from blowing out/off, too much pressure OUT of the compressor