you need to remember that these units are all good units BUT if you have a bad installation or bad sizing with no information then they wont work right. just make sure its PROPERLY installed and that the unit you buy is the correct for the use you need. i understand the allure of those precharged lines but i have hear a lot of bad things. my unit was properly vacuumed and charged to EXACT amount of refrigerant per manufacturer. this is VERY important with these types of heat pumps