The AC compressor in my 99 Durango 5.2 is cycling on and off. It will run for 8 seconds then shut off for 4 seconds. The vents are blowing cold air but just not enough to cool down the interior because the compressor won't stay engaged. What could cause this problem.

 

low charge. Have you checked it?

Second, it does engage intermedeatly to lubricate the moving parts.

 

defidently low charge. My compressor was doing the same thing. One of the gaskets blew out and had to replace the thing. Was pretty easy to do. Get the R124a with the dye in it so you can check for leaks after you fill it.