2003 Buick Regal Air conditioning working backwards

Air Conditioning problem
2003 Buick Regal 6 cyl Front Wheel Drive Automatic 10O3 miles

My air conditioner doesn't work when I get in my car and turn it on. My son was just playing with it one day and he did something to turn it on but the Service engine soon light came on and it will stay on all the time I have it on without any problem but when he put it back the way it suppose to be it won't work. I called him and this is what he said he did: Disconnected the coolant sensor and clutch relay to engage the compressor. I hope I said it correctly. He said the compressor will not engage otherwise.