The best way to locate a heater core hose is to determine where the heater core is located. Many vehicles have the heater core inside the dash. Other vehicles, usually larger vans and trucks, will have a heater core box inside the engine compartment. Once you have determined where the heater core is located in your vehicle, that will allow you to easily locate a heater core hose. If the heater core is inside the dash, you'll need to examine the firewall for the hoses. If it is in a heater box, you'll need to look around the engine compartment for the box.
Heater cores located inside dashes can be very difficult and time consuming to replace. Depending on the layout of your engine compartment, it can also be difficult to locate a heater core hose. If there is very little clearance between the engine and the firewall, you may have difficulty finding the hoses. You might need to use a flashlight to look from the underside in some cases. You will typically be able to identify the heater hoses where they enter the firewall by looking for two two small diameter hoses that protrude into the engine compartment. You can then trace those hoses to their other ends, where they will typically connect to a thermostat housing, the radiator, or a t-connector.
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