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What this kit covers

The Koeep Aluminum Radiator & AC Condenser Cooling Kit fits the 2016-2018 Kia Optima (JF platform), including the 2017 and 2018 model years. It replaces the factory radiator and A/C condenser as a matched pair, and it targets the two documented weak points of this platform: plastic end tanks that crack with heat cycling, and condensers that leak at the mounts.

The radiator is 3003-series aluminum from tank to tank, furnace-brazed, with no plastic in the structure. Koeep rates it at 28-35% more heat rejection than the stock aluminum-core/plastic-tank unit. The condenser uses multi-louvered micro-channel (MLC) tubes and is dual-rated for R-134a and R-1234yf refrigerant.

Why the stock radiator fails

Kia built this Optima generation in West Point, Georgia and Hwasung, Korea. The factory radiator, supplied by Hanon Systems and Denso, pairs an aluminum core with PA66-GF30 tanks (nylon 6/6 with 30% glass fill) crimped onto the headers.

Failure data from NHTSA VOQ submissions and Kia TSB ENG-223 points to one spot: thermal cycling fatigue cracks at the cold-side tank-to-header crimp, typically between 60,000 and 95,000 miles.

The cause is differential thermal expansion. Aluminum expands at about 23 × 10⁻⁶ /°C, PA66 at about 80 × 10⁻⁶ /°C. After roughly 4,000 to 5,500 heat cycles between ambient temperature and the 105°C operating range, stress builds at the gasket land, micro-cracks grow, and the EPDM gasket seal lets go. Coolant leaves slowly, and the first warning is often a P2181 or P0115 code instead of a puddle.

How the all-aluminum build removes the failure mode

Koeep welds the 3003 aluminum tanks and furnace-brazes them to the core with the Nocolok® flux process at about 600°C. Core and tanks are one metal with one expansion rate, so the crack mechanism is gone by design. The unit passed 12,000+ thermal shock cycles from -30°C to +120°C under ISO 8634 without leakage.

The core runs 16mm single-row louvered tubes with a 1.2mm fin pitch against the stock 1.4mm, and heat rejection measures about 18.5 kW at 2.5 m/s air velocity, up from the 14.2 kW OEM figure.

The condenser carries 1.5mm multi-port micro-channel extruded tubes, with subcooling that matches or beats the OEM Hanon unit. R-1234yf readiness matters because Kia has moved this platform (now sold as the K5) to yf refrigerant, which runs about 18 bar on the high side and needs PAG-46/POE oil compatibility.

Specification comparison

The numbers below come from the product's technical data, set against the OEM Hanon/Denso unit for the same years.

Fitment and OEM cross-reference

OEM part numbers

Kia's radiator numbers are 25310-C5000 and 25310-C5100, superseded by 25310-C5200. The superseded part still carries PA66 plastic tanks. OEM condenser numbers are 97606-C5000 and 97606-C5100. The Koeep kit replaces both sides with full-aluminum units.

Years, trims and engines

Coverage runs across the 2016, 2017 and 2018 Optima (JF) in LX, EX, SX and SXL trims, with both engines: the Theta II 2.4L GDI (G4KJ) and the Theta II 2.0L Turbo GDI (G4KH). The two share identical core dimensions and mounting points.

The 2.0T peaks near 195 kW against 138 kW for the 2.4L, so the added heat rejection gives the turbo car headroom under sustained boost. Hyundai Sonata LF (2015-2019) 2.4L and 2.0T variants share the same front-end architecture and are mechanically compatible. Condenser line routing can differ on Sonata Hybrid and Plug-in variants, so match the ports before ordering for those cars.

Materials and test standards

Core and tanks are 3003-series aluminum (ASTM B209 / AMS 4038), brazed under controlled-atmosphere (CAB) conditions with potassium fluoroaluminate flux. The radiator meets SAE J1959 Class B thermal cycling and ISO 8634 pressure cycling at 12,000+ cycles. The condenser is rated under SAE J3062, and every unit is helium leak tested at 10⁻⁹ atm·cc/sec before shipment.

Market context

The 2026 aluminum radiator aftermarket is projected at $8.93 billion globally, inside a total radiator market of $10.34 billion growing at 6.3% CAGR toward $15.86 billion by 2033. The U.S. fleet now averages 12.6 years old. Ford (2025+ Explorer), GM (2026 Traverse/Enclave) and Toyota (2026 Camry) have all moved recent models to brazed-aluminum radiators, the same construction this kit uses.

DTC mapping

• P0480-P0483 (fan control circuit, rationality): restored radiator efficiency lowers fan duty demand, so the codes stop returning.
• P2181 (cooling system performance): caused by micro-leakage at the tank-to-header interface; the aluminum tank removes it.
• P0115-P0119 (ECT sensor circuit): readings normalize once coolant volume is stable again.
• P0530-P0534 (A/C pressure sensor, charge loss): a leak-free condenser with a verified charge closes these out.
• P0070-P0074 (ambient air temp sensor): often disturbed during radiator R&R; check the connector after install.

Kia TSB ENG-223 (cooling system diagnostic flowchart, 2022 update) covers the OEM diagnostic order for these codes. We apply the same code-to-part method across the catalog; the GM/Chevy power mirror DTC guide shows it on a body-electrical system.

Installation and service notes

Professional installation is strongly recommended. The A/C circuit needs refrigerant recovery (venting is prohibited under EPA Section 609, and service requires 609 certification), evacuation below 500 microns, a vacuum leak-down of at least 30 minutes, and a weighed recharge of 500 ± 25g R-134a or 470 ± 20g R-1234yf. A condenser replacement takes 30cc of fresh PAG-46 oil. Retrofitting a car from R-134a to R-1234yf follows SAE J2842 for flush steps and oil compatibility.

On the coolant side, run Hyundai/Kia POAT coolant on the 5-year/60,000-mile interval. With that maintenance the core should outlast the vehicle; the service-life projection is 2026 to 2030 and beyond under normal operating conditions.

Related cooling parts for other Kia and Hyundai models

If you also service a 2014-2016 Kia Soul, the same all-aluminum approach is available as an electric AC condenser cooling fan kit for that car. Owners of the previous Optima generation, or of a 2012-2014 Hyundai Azera, can use the matched aluminum radiator and condenser kit for those years. For the full climate-control catalog, browse the AC & Heating collection.

Frequently asked questions