How to remove and replace the heater core in an automotive HVAC system on Mazda 3?

Begin by having the air conditioning system discharged by an automotive air conditioning technician. Next, remove the battery cover and disconnect the cable from the negative battery terminal. Drain the cooling system, then disconnect the heater hoses from the heater core inlet and outlet pipes at the firewall, along with the two refrigerant pipes. Tag and disconnect the cables and electrical connectors from the HVAC unit, and remove the mounting fasteners from the firewall side of the engine compartment. Remove the instrument panel and HVAC unit as an assembly, and take off the lower cowl grille panel to access some HVAC unit fasteners. Remove the HVAC unit-to-instrument panel mounting fasteners and separate the unit from the instrument panel. The heater core is located in the front lower center section of the HVAC unit, below the blower motor housing; remove the heater core cover screws and pull the heater core out of the housing. Installation is the reverse of removal, ensuring to reconnect the heater core inlet and outlet hoses at the firewall. Finally, refill the cooling system and have the system evacuated, recharged, and leak-tested by the shop that discharged it.

Genuine Mazda 3 Heater Core

HVAC Heater Core

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11 Heater Cores found

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Mazda 3 Heater Core Part Number: BFWM-61-A10
$107.60 MSRP: $143.50
You Save: $35.90 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Core, Heater Unit; Heater Core
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2022-2024 Mazda 3 | 2.5 Carbon Turbo, 2.5 Turbo, 2.5 Turbo Premium Plus | 4 Cyl 2.5 L GAS
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Mazda 3 Heater Core Part Number: BDTS-61-A10
$179.43 MSRP: $239.28
You Save: $59.85 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Core, Heater Unit; Heater Core
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2019-2024 Mazda 3 | 2.0, 2.5 Carbon Turbo, 2.5 S, 2.5 Turbo, 2.5 Turbo Premium Plus, Base, Carbon Edition, Preferred, Premium, Select, Select Sport | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Heater Core Part Number: BJS7-61-A10A
$277.00 MSRP: $369.40
You Save: $92.40 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Core, Heater Unit
- Replaces: BJS7-61-A10
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2014-2018 Mazda 3 | Grand Touring, i Grand Touring, I Sport, i SV, I Touring, s Grand Touring, s Touring, Sport, Touring | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Heater Core Part Number: BP4K-61-A10
$294.11 MSRP: $392.23
You Save: $98.12 (26%)
Ships in 1-2 Business Days
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Product Specifications
- Other Name: Core, Heater Unit
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2004-2008 Mazda 3 | i, Mazdaspeed, S, SP23 | 4 Cyl 2.0 L GAS, 4 Cyl 2.3 L GAS
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Mazda 3 Heater Core Part Number: BBM4-61-A10
$335.11 MSRP: $446.90
You Save: $111.79 (26%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Core, Heater Unit
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2012-2013 Mazda 3 | i, Mazdaspeed, S | 4 Cyl 2.0 L GAS, 4 Cyl 2.3 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Heater Core Part Number: BDGF-61-A10
$359.55 MSRP: $479.50
You Save: $119.95 (26%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Core, Heater Unit; Heater Core
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2019-2024 Mazda 3 | 2.0, 2.5 S, 2.5 Turbo, 2.5 Turbo Premium Plus, Base, Carbon Edition, Preferred, Premium, Select, Select Sport | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Heater Core Part Number: BBM5-61-A10
$397.49 MSRP: $534.37
You Save: $136.88 (26%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Core, Heater Unit
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2010-2013 Mazda 3 | i, Mazdaspeed, S | 4 Cyl 2.0 L GAS, 4 Cyl 2.3 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Heater Core Part Number: GHP9-61-A10
$436.10 MSRP: $586.26
You Save: $150.16 (26%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Core, Heater Unit
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2014-2018 Mazda 3 | Grand Touring, i Grand Touring, I Sport, i SV, I Touring, s Grand Touring, s Touring, Sport, Touring | 4 Cyl 2.0 L GAS, 4 Cyl 2.5 L GAS
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Mazda 3 Heater Core Part Number: BP8P-61-A10
$481.05 MSRP: $646.70
You Save: $165.65 (26%)
Ships in 1-2 Business Days
ADD TO CART
Product Specifications
- Other Name: Core, Heater Unit
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2008-2009 Mazda 3 | i, Mazdaspeed, S | 4 Cyl 2.0 L GAS, 4 Cyl 2.3 L GAS
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Mazda 3 Heater Core Part Number: BBS1-61-A10
Product Specifications
- Other Name: Core, Heater Unit
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2010-2013 Mazda 3 | Mazdaspeed | 4 Cyl 2.3 L GAS
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Mazda 3 Heater Core Part Number: CC99-61-A10
Product Specifications
- Other Name: Core, Heater Unit
- Warranty: This genuine part is guaranteed by Mazda's factory warranty.
Fits the following Vehicles:
- 2007-2009 Mazda 3 | Mazdaspeed, S | 4 Cyl 2.3 L GAS

Mazda 3 Heater Core

The Mazda 3 Heater Core is the part of the cabin that converts waste engine heat into warm air during cold road journeys. It is located under the dashboard in the shape of a mini radiator, fed with hot coolant under pressure by the engine water pump through special hoses, and as the blower pushes air over its finned aluminum or brass tubing, the heat is collected by the air and then directed into the cabin. Two major strategies applied by Mazda to control this flow of warmth, depending on the model year, are a simple coolant valve that meters the amount of liquid introduced into the core or an air-mix door, which guides the ventilation around or through it, providing the occupants with fast control over the temperature. More recent Mazda climate package installations include small electric actuators and thermistor sensors which allow the driver and the passenger to adjust to small personal comfort zones, and when an air conditioning option is chosen, chilled and humidity free air is first passed over the evaporator and only then over the Heater Core, allowing windows to remain clear. The Heater Core also assists the engine by serving as a backup radiator in case the engine needs more cooling. All of them have the same weaknesses, such as clogging due to the lack of necessary coolant changes, leaks at soldered joints, and corrosion due to stray electricity, which are further aggravated by the fact that access to any particular unit requires the removal of much of the dash to reach the needed component. Mazda 3 owners ought therefore to take care of the coolant health to increase the life of this unsung yet important component.

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Mazda 3 Heater Core Parts and Q&A

Heater Core
BP8P-61-A10
Q: How to remove and replace the heater core in an automotive HVAC system on Mazda 3?
A:
Begin by having the air conditioning system discharged by an automotive air conditioning technician. Next, remove the battery cover and disconnect the cable from the negative battery terminal. Drain the cooling system, then disconnect the heater hoses from the heater core inlet and outlet pipes at the firewall, along with the two refrigerant pipes. Tag and disconnect the cables and electrical connectors from the HVAC unit, and remove the mounting fasteners from the firewall side of the engine compartment. Remove the instrument panel and HVAC unit as an assembly, and take off the lower cowl grille panel to access some HVAC unit fasteners. Remove the HVAC unit-to-instrument panel mounting fasteners and separate the unit from the instrument panel. The heater core is located in the front lower center section of the HVAC unit, below the blower motor housing; remove the heater core cover screws and pull the heater core out of the housing. Installation is the reverse of removal, ensuring to reconnect the heater core inlet and outlet hoses at the firewall. Finally, refill the cooling system and have the system evacuated, recharged, and leak-tested by the shop that discharged it.