I haven't posted in years,but having an issue. My blazer is factory ac,but i deleted it. I just want defrost for cold mornings for windshield. I dont have a vacuum line from engine to interior. I have the dash mostly apart and heater assembly removed. Do i need vacuum for just the defrost? The vacuum line scenario in my blazer is sketchy at best,lots of loose ends. I marked the ones that were still attached. I just want to be able to defog windshield if needed,im in norcal,and dont drive it much in the winter,or much at all really,lol.