I need help
 

I have a cadillac deville 03 and my ac and heater do not work at all in the front of the car. The back seat vent does work. The back seat vent I used today and it blew out warm air but took a very long time and I had to be on the highway for it to start blowing out hot air. So in recap my front door rear view mirror vents, defrost, and front seat vents all do not work anymore. My middle counsel back seat vent does work. I have not been able to research the issue on the car yet because I do not know much about my car because I just got it not too long ago. The ac and heater did work before but during summer it started to work when it wanted to and eventually it stopped working. I could even slam my fist on the dash board and I would get lucky and it would turn on. But not anymore. Someone please help me!