I have a 2003 Durango 4.7, 4x2 single zone a/c, the A/C button is constantly on and the compressor will not come on. I have checked the low side pressure and it was WNL for the ambient temp. I also have replaced the low pressure cut off switch. But wait I am not done. I have replaced the control head and had the pcm flashed. With the replacement control unit I believe it started to flash the defrost light and the A/C light would not come on nor would the a/c work(this is the unit I used when flashing the pcm). Since it did not work the dealer refunded my money and put the original unit back (but they also tried to flash the pcm with this on too). And it is the original control head installed with the A/C light constantly on. Here is a catch to all of this I ran a bypass from the light blue with black tracer at the compressor directly to the battery and the a/c blows cold enough to freeze the low side line and will produce a vent temperature below 50 deg. F with all but one vent closed. But the compressor will not cycle. FRUSTRATED!