• 2021

Core Workout

Heater Core Replacement in a 2013 Chrysler 200

A vehicle heater is a rather simple device, including a heater core, which is basically a heat exchanger and the
heater box; an assembly containing air passages; and gates that direct air into the passenger cabin. Replacing a vehicle heater core, however, is a complex repair process. And, like a person’s core fitness is crucial to the rest of the body, a properly functioning heater core is foundational to the rest of the heater’s proper operations.

Heater Basics

Let’s take a look at the entire heater/AC system and see how it works (Figure 1). The heating/AC system pulls outside (ambient) air through the fresh air intake ④ located at the cowl panel at the base of the windshield and into the air inlet housing above the heating, ventilation and air conditioning (HVAC) housing and passes through the A/C evaporator ⑦. Air flow is then directed either through or around the heater core ②. This is done by adjusting the position of the blend-air door ③ with the temperature control located on the A/C-heater control in the instrument panel. Air flow is then directed out the floor outlet ⑧, instrument panel outlet ⑩ or the defroster outlet ① in various combinations by adjusting the position of the mode-air doors (⑨ and ⑪) using the mode control located on the A/C-heater control. The temperature and mode control uses electrical actuators to operate the air doors.

Figure 1

Figure 1

The heater core ① for the heater/AC system (refer to Figure 2), is mounted within the HVAC air distribution housing, described above, which is located behind the instrument panel. The heater core is a heat exchanger made of rows of tubes with fins and is positioned within the air distribution housing so that only the selected amount of air entering the housing passes through the heater core before it is distributed through the heater/AC system ducts and outlets.

Figure 2

Figure 2

One end of the heater core is fitted with a tank (2) that includes the fittings for the heater core tubes (3). The heater core can only be serviced by removing the HVAC housing from the vehicle.

Engine coolant is circulated through the heater hoses to the heater core at all times. As the coolant flows through the heater core, heat is removed from the engine and is transferred to the heater core tubes and fins. Air directed through the heater core picks up the heat from the heater core fins.

Heater Performance

The first sign that there is a potential problem with the heater core is the lack of heat when the heater is used. It might seem like the temperature of the heated air doesn’t seem as warm as it used to be. This is similar to an AC problem in the summer when the air being blown out of the dashboard panels just isn’t as cold as it was last summer. It’s unlikely that the heater just won’t blow warm anymore, unless a door is blocked, or its actuator is broken. So let’s review the steps to checking heater performance.

First check the following items: ① engine coolant level and flow, ② engine coolant reserve/recovery system operation, ③ accessory drive belt condition and tension, and ④ radiator air flow and fan drive operation.

With the engine idling at normal operating temperature, set the temperature control to the full hot position, the mode control to the floor position, and the blower motor control to the highest speed position. Using a test thermometer, check the temperature of the air being discharged at the front floor outlets. Compare the test thermometer reading to the Heater Temperature Reference chart below:

Temperature Chart

Temperature Chart


If the heater outlet temperature is below the minimum, there is a problem in the heater core. Both heater hoses
should be hot with the return hose slightly cooler. If the heater return hose is much cooler than the supply hose, there is an obstruction in the core. On some older models, the heater cores become blocked by a gel-like substance (Figure 3). When the core is blocked, it must be replaced.


Figure 3

Figure 3


Heater Core Replacement

While the heater core is a relatively simple component with no moving parts, replacing it is not simple. The HVAC housing assembly, along with the left side front floor duct, must be removed.

It’s a complex repair. Removing these components, while being similar to other vehicles, does vary from vehicle to vehicle, so be sure to check the specific service manual for the vehicle being repaired.

Before getting started, some work outside of the passenger compartment must be done. This includes disconnecting the AC liquid and suction line assembly from the evaporator and disconnecting the heater hoses from the heater core tubes.

Be sure to plug, or tape over, the heater core tubes and AC line fittings to prevent any spillage of fluids inside the vehicle. Also, cover the floor inside the car in case any fluids do spill when removing the HVAC housing assembly.

Figure 4

Figure 4

After removing the HVAC housing and front floor ducts from the vehicle, place the housing on a flat work surface. Refer to Figure 4. Remove the foam seal ① from the flange ② located on the front of the housing ⑦. Then, remove the screw ⑧ that secures the flange to the front of the housing, then remove the flange.

Next, remove the heater core tube retaining brackets ⑥ that are mounted on the side of the housing ④. Two screws ③ hold these brackets in place. After the brackets are removed, slowly and carefully pull the heater core ⑤ out of the driver side of the air distribution housing.

With the old core removed, carefully install the new heater core ⑤ into the housing ④. Position the heater core tube brackets ⑥ in place. Secure the brackets with the two screws ③ and tighten the screws to 10 in-lbs. Install the flange ② and tighten the retaining screw ⑧ to 10 in-lbs. Install the foam seal.

Next, re-install the left side front floor duct, then re-install HVAC housing assembly. Flush the cooling system, then reconnect the heater hoses to the heater core tubes. Remove the tape, or plugs, from the refrigerant line fittings and evaporator ports. Lubricate the rubber O-rings before reconnecting the lines.

IMPORTANT: Use the required coolant of the vehicle; do not mix coolants or use something other than what is required. Mixing coolant can lead to heater core plugging and repeat failures.

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