There is a 3 pin temp sensor at the front of the cylinder head(red or green). It is for the aux. fan & overheating for the A/C system. If the switch thinks the engine is too hot then it will cycle the compressor as described. There is a 2 pin connector for the aux fan & the single pin is for the overheating a/c comp. shutoff. Try disconnecting the single pin the next time & see if a/c stays on. If that fixes it then install a new switch.