I don't remember where I learned this but this has helped me and a few others when either the A/C or heat acts up, usually after either replacing the battery, an actuator, or HVAC control head. First, start the engine and turn all the controls to the off position, (rear controls too if they're acting up) , temp turned all the way down. Shut off the engine. Remove the positive battery terminal and leave it off for 10 minutes. When it's time to reconnect it, touch it to the negative battery terminal to make sure any residual electricity is discharged. Start the engine and DO NOT TOUCH THE HVAC CONTROLS FOR 5-10 MINUTES! The system will go through a calibration procedure, all the actuators ( mode, blend, recirc) will calibrate also. Then you can try out all the functions; heat, A/C, fan, etc and hopefully all will be working correctly. This also worked for my rear A/C when I pulled out the control head and reinstalled it a few days later only to find my rear A/C didn't work anymore.