In my 96 sunfire i did the ecotec swap with minimal components swapped over. So, i dont have a bcm that the new pcm can communicate with. Well after three years of that being ok i decide to finally get a/c to work. Well, after more money then the car is worth into it i still dont have a/c... Come to find out that on the newer communication systems that the hvac tells the bcm to send a messege to the pcm to command the compressor clutch if the low pressure switch will allow... Well how the hell do i get this to work without swapping an entire interior harness and bcm... I cant just make a ghetto switch to command the clutch cause that will bypass the low pressure switch and then it builds up enough pressure to go out the compressor relief...

Any help and crazy ideas will be greatly appreciated. Thanks

Low pressure switch won't affect how the compressor runs. The low pressure switch is to shut the compressor off if there is no pressure due to no freon, I'm pretty sure you can wire it in series with the compressor and it will work tge same as before, just wire it up to your hvac controls.