the heater core can be replaced by draining the cooling system, disconnectiong the battery, removing the center console and underdash sound insulator panels. then remove the heater core cover and the heater core. Reverse the procedure to reinstall it.
RepairPal Certified shops can diagnose and repair your 2000 Chevrolet Monte Carlo. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.