2001Montana Issues again

Well I am back at the old Montana trying to figure out why the radiator fans will not work properly. The one will not kick on even when I turn the air on. I have tried everything. I have replaced the coolant temp sensor and the thermostat. I have ran a toggle switch to the fan that is supoose to come on when the A/C is on and the fans do work that way. It is odd that both will work when the toggle switch is on, But I only have the one wired up. The wires get warm to the toggle switch and it is size 10 wire. Any solutions out there. All relays have been replaced. Also the ground wire to the fans has been cut and it has been bolted to the block. Not by me. Could it be the ECM not sending the command to fans to come on. Any way to check. Please reply soon.