Truck Repair: a/c and abs light, intermittent problems, c3500

Question
I ran across this site and hopefully you can help. I have spent over $800 already and have gotten no where. My a/c has been having intermittent problems. It will go off and sometimes take forever before it will kick back on. They replaced the compressor last week. Checked the control head ? and it was fine. I am still having the same problems though. I noticed today that it will be running fine and if I move the dial to adjust high/low it turns off and immediately the abs light on my dash comes on. It is a chevy C3500 diesel. Thanks

Answer
Hello Amanda,
That sounds like a loose connection or ground wire.
Check where all the wires go through the firewall...just wiggle and oush it together.
Aslo check on the right side of the intake manifold near the firewall. There should be a ground strap or wire from the engine to the firewall. make sure it is tight.
Van