so I posted this before but now I'm going to do an update. My 02 4.6is has had serious issues with the heater not working as in the heater will work for about 5 minutes but then the display and heater together will flicker off and on. My indy and I have replaced the HVAC control unit 3 times, FSR, tries unplugging ambient temp sensor, nothing has worked!. AC works just fine but the second I crank up the temp and roll the dial on the vents to red it starts giving me issues. Please anyone help!

Thanks!!