The relay is mounted on the driver's side of the engine bay, in the fuse and relay box below the dashboard

The radiator cooling fan motor relay in a 2000 Acura TL sits in the under-dash fuse box on the driver's side, not in the engine compartment relay box. This is the small black plastic box mounted beneath the steering column, accessible without removing any trim. The relay itself is a square module about the size of a matchbox, and you'll find it labeled in the diagram printed on the inside of the fuse box cover.

The exact position varies slightly depending on whether your TL has the base engine (3.2L V6) or the Type-S engine (3.2L V6 with higher output), but both use the same under-dash location. You do not need to remove the steering wheel, dashboard, or any major components to reach it. The fuse box is designed for owner access, and the relay pulls straight out once you locate it.

Key Takeaways

  • The cooling fan relay is in the under-dash fuse box on the driver's side, not under the hood.
  • The relay is labeled on the diagram inside the fuse box cover, so you can identify it before touching anything.
  • The relay pulls straight out by hand; no tools are required to remove or replace it.
  • A failed relay will prevent the cooling fan from running even when the engine temperature rises, which can lead to overheating.

How to access the under-dash fuse box

Sit in the driver's seat and look up at the underside of the dashboard, just to the left of the steering column. You will see a black plastic box with a removable cover. The cover is held in place by a clip or a single screw, depending on the year and trim level. Open or remove the cover to expose the fuses and relays inside.

The diagram on the inside of the cover shows every fuse and relay position. Find the label that reads "Cooling Fan Motor Relay" or "Radiator Fan Relay" — the exact wording varies between model years, but the function is the same. Once you locate the position on the diagram, count the rows and columns to find the matching slot in the fuse box itself.

What the relay looks like and how to test it

The cooling fan relay is a black plastic cube with four metal pins on the bottom. It is larger than a fuse but smaller than a typical automotive relay you might see in an engine bay. When you pull it out, the slot will be empty and you can see the four pin holes clearly.

A straightforward test is to swap the relay with another relay of the same type from a different circuit — many relays in the 2000 TL are interchangeable. If the cooling fan runs after you swap them, the original relay is faulty. If the fan still does not run, the problem is likely in the wiring, the fan motor itself, or the engine temperature sensor that signals the relay to close. A multimeter can also test the relay's continuity, but the swap test is faster and requires no special equipment.

Common reasons the relay fails

The cooling fan relay fails most often because of age and heat exposure. Even though it sits under the dashboard away from direct engine heat, it still experiences temperature swings every time the engine runs. After 20+ years, the internal contacts wear out and no longer close reliably when the engine temperature rises.

Moisture and corrosion can also damage the relay pins. If water has entered the fuse box — from a leaking windshield seal, a clogged cabin air filter drain, or a flooded cabin — the relay contacts may corrode and fail to conduct current. In these cases, replacing the relay alone may not solve the problem; you may also need to dry out the fuse box and check the wiring for corrosion.

Symptoms of a failed cooling fan relay

The most obvious sign is that the radiator cooling fan does not spin when the engine is hot. You can test this by starting the engine and letting it idle for five to ten minutes. Feel the radiator hose — if it becomes hot but the fan does not turn on, the relay is likely the culprit. You may also notice the engine temperature gauge climbing higher than normal, or the cooling fan running only intermittently instead of staying on consistently.

Some owners report that the fan runs only after the engine reaches very high temperatures, or that it shuts off and restarts erratically. This behavior suggests the relay contacts are corroded and making poor contact, rather than a complete failure. In either case, replacement is the most reliable fix.

Replacement and part numbers

Replacement relays for the 2000 Acura TL cooling fan circuit are inexpensive, typically between $15 and $40 depending on the supplier. Acura part number 39794-SDA-A01 is the OEM relay for most 2000 TL models. Aftermarket relays from suppliers like Standard Motor Products or Bosch are also available and perform identically.

Installation takes less than five minutes: pull out the old relay, insert the new one into the same slot, and close the fuse box cover. No wiring, soldering, or adjustment is needed. If the fan runs when ready after installation, the relay was the problem. If the fan still does not run, have the wiring and temperature sensor checked by a technician before replacing any other components.

When to check the relay versus other cooling system parts

The relay is the first thing to check if the fan does not run at all, because it is cheap and straightforward to replace. If the fan runs but the engine still overheats, the problem is likely the thermostat, water pump, or radiator itself — not the relay. If the fan runs constantly even when the engine is cold, the relay may be stuck in the closed position, but this is less common than a relay that fails to close.

If you replace the relay and the fan still does not respond to engine temperature, have a technician test the engine coolant temperature sensor (ECT sensor) with a scan tool. The ECT sensor tells the engine computer when to signal the relay to turn on the fan. A faulty sensor will prevent the relay from receiving the signal, even if the relay itself is working correctly.

Frequently Asked Questions

Can I drive the car if the cooling fan relay is broken?

You can drive it for short distances in cool weather, but the engine will overheat in traffic or on hot days. The radiator alone cannot cool the engine without the fan running. Stop and let the engine cool if the temperature gauge climbs into the red zone, and replace the relay as soon as possible.

Is the cooling fan relay the same as the condenser fan relay?

No. The 2000 TL has separate relays for the radiator cooling fan and the air conditioning condenser fan. They are in the same fuse box but in different positions. Check the diagram on the fuse box cover to make sure you are replacing the correct one.

What if I pull out the relay and the fan suddenly starts running?

This can happen if the relay was stuck in the closed position, allowing current to flow constantly. Reinstall the relay and test it again. If the fan turns off and on normally with engine temperature, the relay may be recovering. If it gets stuck again, replace it.

Do I need any special tools to replace the relay?

No. The relay pulls straight out by hand, and the fuse box cover opens with a screwdriver or by hand depending on the fastener type. You do not need a multimeter, scan tool, or any diagnostic equipment to swap the relay.