2017-2021 Honda Clarity Fuel Cell Intercooler: A Guide to the FCEV-Specific Component

Critical Compatibility Warning: Fuel Cell Models Only

Function of the Clarity Fuel Cell Intercooler

Unlike a traditional gasoline car, the Clarity Fuel Cell doesn't have an internal combustion engine. Instead, it has a fuel cell stack that combines hydrogen and oxygen to create electricity, with water as the only byproduct. To generate power efficiently, the stack needs a steady supply of highly compressed oxygen. An electric compressor, similar in principle to a turbocharger's compressor side, provides this pressurized air. However, compressing air makes it very hot. Hot air is less dense and can reduce the fuel cell's performance and lifespan.

This is where the intercooler comes in. It's a heat exchanger that cools the hot compressed air before it enters the fuel cell stack. The Clarity uses a liquid-cooled (or water-to-air) system, which is more compact and efficient than a typical air-to-air intercooler. This system circulates a special coolant, called FC insulating fluid, through the intercooler to absorb heat from the charge air, and then dissipates that heat through a separate, low-temperature radiator.

Common Symptoms of a Failing Intercooler

While there are no widespread reported failures for this specific part due to the vehicle's rarity, a faulty intercooler on the Clarity Fuel Cell would exhibit symptoms similar to those in other vehicles with water-to-air intercoolers.

Reduced Power and Sluggish Acceleration

This is the most likely symptom. If the intercooler is leaking or clogged, it cannot cool the compressed air effectively. The vehicle's control unit may detect the higher intake air temperatures and reduce power output to protect the fuel cell stack, making the car feel sluggish. In severe cases, the system may enter a reduced power "limp mode".

Hissing or Whistling Noises

A distinct hissing or whooshing sound during acceleration is a classic sign of a boost leak. This noise is caused by compressed air escaping from a crack in the intercooler body, a damaged hose, or a loose connection. The sound will be most noticeable when the air compressor is working its hardest.

Visible Coolant Leaks

Since this is a water-to-air unit, it can develop internal or external coolant leaks. You might notice puddles of the specialized FC insulating fluid under the vehicle. A leak can also occur internally, allowing coolant to mix with the charge air, which could potentially damage the fuel cell stack over time.

Power System Warning Lights

A significant leak or clog in the intercooler system can trigger a fault in the powertrain control module. This would likely illuminate a general power system warning light on the dashboard, prompting the driver to seek service.

Known Issues, Recalls, and Service Bulletins

As of late 2023, there are no specific recalls or Technical Service Bulletins (TSBs) issued by Honda or the NHTSA for the intercooler itself on the 2017-2021 Clarity Fuel Cell. However, there are several important recalls for related systems that can cause similar symptoms.

• NHTSA Recall 19V315000: This recall addresses an electric water pump that can corrode and fail. This pump is a critical part of the fuel cell cooling system. Its failure can cause the fuel cell stack to shut down to prevent overheating, resulting in a sudden loss of power.
• NHTSA Recalls 18V068000 & 18V921000: These recalls are for a software issue in the Fuel Cell Electronic Control Unit (FC-ECU). The software could misinterpret a normal voltage drop, causing it to shut down the fuel cell stack and lead to a loss of power.
• TSB A19-006: This bulletin addresses accelerated deterioration of the fuel cell stack due to improper water discharge inside the unit. The corrective action is to replace the entire fuel cell stack.

Buying a Used Intercooler: What to Check

Finding a used intercooler for a Clarity Fuel Cell will be challenging due to the extremely low number of these vehicles produced. If you do find one, careful inspection is critical.

1. Confirm the Source Vehicle: Absolutely confirm the part came from a 2017-2021 Honda Clarity Fuel Cell. Ask the seller for the VIN of the donor car if possible. A part from a Plug-In Hybrid will not work.
2. Physical Inspection: Carefully inspect the entire unit for cracks, especially where plastic end tanks are joined to the aluminum core. Check for signs of corrosion on the aluminum. Look for bent or damaged cooling fins; while a few are acceptable, major damage can restrict airflow and cooling.
3. Check for Leaks: Look for any signs of dried coolant residue (chalky white or colored stains) around hose connections or seams, which indicates a past leak.
4. Internal Inspection: Look inside the inlet and outlet ports. The inside should be clean and dry. The presence of significant oily residue or coolant is a major red flag, indicating potential problems with other components on the donor vehicle.
5. Verify Part Numbers: Match the part number on the unit to the known OEM numbers: 3G011-5WM-A00 or 3G660-5WM-A01.

Replacement Information

• Installation Difficulty: 5 out of 5 (Expert, Dealer-Only)
• Reasoning: The intercooler is deeply integrated with the fuel cell stack and its cooling and air intake plumbing. Replacement requires draining the specialized FC insulating fluid, safely disabling the high-voltage system, and potentially removing parts of the fuel cell powertrain assembly.

Cost Comparison

Due to the specialized nature of this vehicle, aftermarket options are not available. Costs are high due to the low production volume.

Frequently Asked Questions (FAQ)