No heat/cold air, temperature gauge does not work?

I am having problems where there is no cold or hot air coming out of the vents, just cool air. After we shut off the car/engine, the radiator fan continues to run for approximately 5 min. The blend door actuator was changed (it was clicking every time we turned on the air). That only solved the clicking. Our temperature gauge is not working either (the only thing on the dash cluster that isn't working). We changed the thermostat and cooling sensor, it worked for maybe 10 miles down the road before the gauge was back at 0, and the problem continues. I unplugged the battery connectors and after i plug them back in and run the vehicle, the temp gauge will work for a while, then back to 0, and back to the fan running after shutting off. Also, there is still no heat, or A/C, just cool air. I have brought up it bring a problem in the wiring, but I am stumped. Any ideas will be helpful that i haven't already tried. Thank you