Q: heater ac blower has no power bad ground wire

On your vehicle, the ground may be switched through a controller. If you bypass the controller and directly ground the blower it will run at only one speed, namely high. If you do not have the vehicle wiring diagram, or at least a voltmeter, it will be risky to make any circuit changes because if a short circuit were to occur, or other mis-wiring, that could damage other vehicle electronics and possibly cause injury (batteries store lots of amps). Your best bet, and really the cheapest option, is to just have the blower circuit diagnosed and if it is indeed the controller (or resistor block), the mechanic will be in a position to fix it right then and there, once the part is obtained. To request that service please use YourMechanic’s blower motor circuit/resistor block service page. If you have further questions or concerns as you decide what to do, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you get the best possible results.