Ghost in my AC

My AC in my 2004 Silverado works fine once I start the truck then about 15 minutes down the road it then starts blowing out heat. I cut off the truck and then back on and then it works fine again. It does this ever three to 4 days. I have cleaned the filter and replace a reset switc ( cant remember what the switch part name is) What do you think is wrong?

Most likely low refrigerant level. Take your truck to an independent automotive AC specialist. They’ll fix you up.