A Guy I know told me that- If your compressor is coming on and off, then on again, it means you do not have enough pressure in the low pressure side to keep the switch being closed, which disengages the compressor clutch until the psi builds up, then it comes on again. Is this correct?

 

yes its to keep the compressor from pumping into a vacuum or running with no gas in it. You need a set of gauges to know what is going on

 

why not just do this. its what I have and it fits the top line.

 

Yeah that's the same gauge I have. It only fits the low pressure side. From what I have been reading if you want to really know its pressure you need the high side gauge and the DIY kits like that don't have a high gauge. Ac manifold gauge is $55 at auto zone.