ALLDATA LLC
09/01/2026 | Press release | Distributed by Public on 09/01/2026 09:20
Engine Cooling Fan Low Speed Problem? Check the Resistor
In an effort to improve fuel economy, and reduce unnecessary engine load, mechanical engine-driven cooling fans have largely given way to electric cooling fans. Depending on the application, these systems may use high and low speed relays or a PCM-controlled pulse-width modulated (PWM) signal sent to a fan control module.
Many dual- and three-speed relay-controlled systems use a separate resistor in the low-speed fan circuit. Of the various types of electric cooling fan speed controls, the low-speed resistor can be one of the more perplexing for technicians. In some cases, the resistor isn't obvious because resistors come in different shapes, sizes, and can be found in different locations, so it's easy to focus on the fan relays and overlook the resistor in the circuit. Because of their location and the heat they handle, these resistors can fail and cause a loss of low-speed fan operation.
Always verify the cooling fan circuit for the specific vehicle and application. Common locations:
Ford Focus & Taurus: Mounted directly on the top or face of the radiator cooling fan shroud and held by plastic clips or screws. It may be easily visible under the hood near the upper core support.
Dodge Grand Caravan & Journey: Plugged directly into the plastic radiator fan shroud near the electric fan motor and positioned to receive airflow through the radiator.
Hyundai & Kia: Positioned in-line with the radiator fan motor wiring harness and often mounted to the fan housing or a nearby bracket with a small bolt or screw.
The wiring diagram and component locations are your friend. Before testing the resistor, use the diagram to verify how the fan circuit operates on that particular vehicle.
One symptom of a failed resistor means the air conditioning grows warmer while the vehicle is stopped. The engine may run slightly hotter in traffic, with temperatures returning to normal once the vehicle begins moving and airflow increases.
Here are a few examples of vehicles that may use a cooling fan resistor:
Ford
- Focus (2000-2011)
- Taurus (2000-2007)
Chrysler
- Grand Caravan (2008-2020)
- Journey (2009-2019)
- Durango (2011-2020)
- Ram 1500 (2002-2008)
Chevrolet / GM
- Cruze (2011-2015)
- Sonic (2012-2020)
- Cobalt (2005-2010)
Saturn
- Ion (2003-2007)
A resistor can be tested simply by doing a voltage test, but first make sure the circuit is commanded on. In many cases, you can monitor the scan tool to verify engine temp is within the range where low speed range should be commanded and also that the PCM isn't using a failsafe strategy because of a related fault.
On some applications, certain recognized faults may cause the PCM to default to high fan speed in an attempt to prevent engine overheating.
If your scan tool has bidirectional controls, you may be able to command low-speed fan operation directly. If not, with the circuit powered down and the resistor disconnected, you can check the resistor using the ohm scale on your meter. An OL reading indicates an open circuit.
Checking the resistor first will save time, keep repair costs down, and keep your customers coming back.
ALLDATA LLC published this content on September 01, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on September 01, 2026 at 15:20 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]