Heater/AC issue

Okay my car has been not cutting the ac/heat on and off at the temp I request but i believe its a sensor. My car always reads the outside temp as -30 and the inside temp is always about 30 degrees off also its either exactly 30 over or under. I was told its 2 different sensors but I can not find anything that seems like it may be that sensor on autozones website and when i called they said their computer shows nothing like that for my car but if I could get a part number they could order it from their wearhouse.

Does anyone know the exact name of these sensors or their part numbers?

Also it is time for me to recharge my ac I was going to do it last summer but I made it through it without really needing it. Next year I fear it won't be as easy, my car is a 1987 oldsmobile regency brougham will I need to take it in to get converted or will they be able to just recharge it I have no idea what refrigerant is currently in the car.