The heater core, which acts like a small radiator for a vehicle's heating system, is installed below the dashboard on the passenger side on a 1993 Chevy S-10 truck. On this model, you don't have to completely remove the dashboard to access the heater core like you do on many other vehicles. The heater core used in this truck is larger those used on some newer vehicles.
Disconnect the truck's negative battery cable.
Open the drain plug at the bottom of the radiator and drain the engine coolant into a large container.
Disconnect the heater hoses from the engine compartment side of the firewall by loosening the hoses' clamps with pliers.
Reach underneath the dashboard in the passenger compartment and remove the screws securing the heater core's rear cover to the cowl using a screwdriver. Remove the cover.
Loosen and remove the strap or bracket retainers for the heater core using the screwdriver, then remove the heater core from its cowl and case.
Insert the heater core into the case and the core's tubes through the cowl, making sure you don't damage the tubes. Install the brackets or straps at the ends of the core and secure them with the retaining screws.
Connect the heater core's rear cover and secure its retaining screws with the screwdriver.
Connect the heater hoses to the core tubes through the firewall in the engine compartment then reconnect the negative battery cable.
Refill the engine coolant in the radiator, making sure you've closed the drain plug underneath. Use a fresh mixture of antifreeze and water if the old coolant is dirty.
