My tech tells me my Drier rusted out and is leaking and we need to replace. What is it anyways, Every unit should have one and they are made of steel and material called a desiccant. As the refrigerant circulates the drier removes any dirt, moisture and acids from the system. Once there In, they remain in. Its important for driers to be coated during a maintenance to prevent rusting. This is something every tech should look for. This will insure a long system like. And yes every unit should have a new one installed anytime refrigerant lines are opened. go to my blog were there are other helpful hints at toroccoscoolingandheating.com. W for world press
