GM Repair Problems? Ask GM Repair Expert Now.
Hello, my name is Bobby. Thank you for the question. This is a common issue. When you say that you replaced the resistor pack was it the blower control module?
Thank you. It sounds like you replaced the module. The module is usually the issue. The fan should not ever come on if the switch is off and the key is off. If the switch is on and the key is off then it may have a bad ignition switch. If it is coming on when the key is off and the switch it off then there is an electrical short in the wiring. Some of the time it is on the back side of the control module.
Do you have remote start also or just locking?
Thank you. If the fan is coming on before the key is on then you either have a failing ignition switch or a body control module problem. Unless the vehicle has been modified in some way the blower should only receive voltage with the key on and the system on. Does a lot of air come from the vents when this turns on?
Does the fan turn off right when you open the vehicle door?
Please let me know as that can give us another clue as to what is causing this. If it stays on suspect the ignition switch. If it goes off then it may be the body control module.