Keystone HO3128101 Aluminum HVAC Heater Core OEM Replacement 79110S9AA01

The Keystone HO3128101 is an OEM-replacement aluminum HVAC heater core designed to restore proper cabin heating performance. This direct-fit unit replaces Honda OEM part number 79110S9AA01 (also cross-referenced as 79110SCAA01) and is built to match original equipment specifications for a precise, reliable fit.

How It Works:

The heater core functions as a small radiator mounted beneath the dashboard. Hot engine coolant circulates through its internal tubes while the blower motor forces air across the aluminum fins, transferring heat into the cabin. A failed or leaking heater core results in loss of cabin heat, fogged windows, a sweet coolant smell inside the vehicle, or visible coolant loss.

Key Features:

• Core Size: 4-1/16 in. (W) x 11-11/16 in. (H) x 1 in. (D)
• Inlet/Outlet Diameter: 5/8 in.
• Material: Aluminum construction with louvered fins for efficient heat transfer
• Direct Fit: Drop-in replacement engineered to OEM dimensions — no modifications required
• OEM Cross-Reference: Replaces Honda part # 79110S9AA01 / 79110SCAA01
• Partslink Number: HO3128101

Installation requires draining the cooling system and removing the dashboard assembly to access the heater box. It is recommended to inspect and replace heater hoses, clamps, and any seals or grommets during installation.