Any advice on changing a heater core? Is this something I can attempt myself with little mechanic skills or should I take it to the shop?
To help me and others answer your question, it would be helpful to know thew year and model of your car. Different cars require different levels of work. The replacement of a heater core is no more difficult that replacing a radiator but typically is done from both sides of the firewall with the core actually coming out from inside the passenger compartment. Space is tight and can be a real obstacle for some owners to tackle themselves.