what would cause the airconditioner and heater both to not work?

it is blowing. the air temperature is not working when it is on high it is barely warm and when it is on air condition it is not cold. it is blowing. Thank you for looking at my question. I even checked the fuse for the air conditioner and it is fine.

On my 2008 Kia Optima, even though the air settings seemed to be working for both heating and cooling, the heat was putting out barely warm air and when I tried the air conditioning, the air was barely cool. On Air Conditioning, with the temp indicator turned down low, the air compressor was coming on, but no cold air was coming from the vents. When the heat was on, and the engine was warmed up to operating temp, warm air would not come out of the vents even though everything indicated that it should be. I checked all fuses and that wasn't the problem. Since both heat and air conditioning stopped at the same time (one day was warm enough for air conditioning and then it turned off cold the next day - that's when I noticed the heat wasn't working. What my problem was turned out to be the "Blend Door Actuator". It cost me $200 in parts and labor to find that out but I could not find any solutions on the internet as I can usually find to see if it is something i can fix myself or if it so complicated that I would have to have a mechanic look at it. In this case, I had to go the mechanic route, but it fixed the problem. I wish you luck and hope you got it resolved.