Cooling System Switches, Sensors & Relays

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    • Bosch® - Coolant Temperature Sensor
      (0 reviews)
      # sp5723
      Coolant Temperature Sensor by Bosch®. Bosch liquid temperature sensors accurately monitor the vital fluids in your vehicle ensuring long and healthy life. The sensor provides information to the Engine control Unit to keep your engine...
      Extreme Temperature range: -40°F to +260°FRobust Design with High Resistance to Engine Vibrations
      $6.68 - $42.61
    • Four Seasons® - Radiator Fan Controller Relay
      (0 reviews)
      # sp95475
      Radiator Fan Controller Relay by Four Seasons®. All products are engineered and tested to provide years of trouble free operation. Backed by over 50 years of car parts experience, fix it once and fix it right with Four Seasons.
      OE quality parts from top original equipment and aftermarket manufacturersThe finest quality at a great price
      $29.34 - $129.24
    • Beck Arnley® - Engine Cooling Fan Module
      (0 reviews)
      # sp9553
      Engine Cooling Fan Module by Beck Arnley®. For one hundred years, Beck Arnley has been providing premium OE quality parts for vehicles. Beginning with motorcycle parts in 1914 and transitioning to import vehicles in the 1950’s, brand...
      OE quality products from top original equipmentTop quality materials
      $34.49 - $264.71
    • ACDelco® - Professional™ Engine Cooling Fan Switch
      (0 reviews)
      # sp114912
      Professional™ Engine Cooling Fan Switch by ACDelco®. Keep your engine cool while utilizing your Air Conditioning System with an ACDelco Engine Cooling Motor. Designed utilizing the latest technology, this product by ACDelco features...
      Conventional and low profile.Space- and weight-efficient.
      +1
      $2.35 - $60.50
    • Dorman® - Radiator Fan Module
      (0 reviews)
      # sp114805
      Radiator Fan Module by Dorman®. Dorman offers a comprehensive line of Radiator Fan Modules for a range of applications. All the Radiator Fan Modules are constructed from high-quality materials for long-lasting durability.
      Easy to installDirect replacement for a proper fit
      $61.97 - $210.59
    • Gates® - Cooling Fan Module
      (0 reviews)
      # sp113802
      Cooling Fan Module by Gates®. If you want to keep your vehicle safe on the road for many years to come, go with this Gates product. Developed with the utmost attention to detail and manufactured from the highest quality materials, it is...
      Great design and functionMade from sturdy materials
      $17.54 - $367.03
    • Calorstat® - Engine Coolant Temperature Sensor
      (0 reviews)
      # sp19598
      Engine Coolant Temperature Sensor by Calorstat®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $3.77 - $20.25
    • FAE® - Auxiliary Fan Switch
      (0 reviews)
      # sp134213
      Auxiliary Fan Switch by FAE®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $6.04 - $37.71
    • Mopar® - Engine Coolant Temperature Sensor
      (0 reviews)
      # sp114778
      Engine Coolant Temperature Sensor by Mopar®. Extend the service life of your engine and make it running smoothly with this high-quality product by Mopar. This part was specially designed to maintain the efficiency and performance of...
      Carefully crafted from premium materialsExcellent corrosion and wear resistance
      $20.55 - $32.73
    • Original Engine Management® - Engine Cooling Fan Motor Relay
      (0 reviews)
      # sp158567
      Engine Cooling Fan Motor Relay by Original Engine Management®. OEM offers the highest quality parts available. With vehicle systems becoming more and more complex, electronic components and sensors must be manufactured to precise...
      Made to deliver trouble-free operation for years aheadManufactured with cutting-edge technology
      $6.84
    • Original Engine Management® - Radiator Fan Switch
      (0 reviews)
      # sp127304
      Radiator Fan Switch by Original Engine Management®. Original Engine Management has the most complete line of High Quality and Value radiator fan switches. Unlike a number of other manufacturers who over-consolidate this critical...
      Made to deliver trouble-free operation for years aheadManufactured with cutting-edge technology
      $7.56 - $26.89
    • URO Parts® - Auxiliary Fan Control Module
      (0 reviews)
      # mpn924410
      Auxiliary Fan Control Module by URO Parts®. Location: Fan. To keep your vehicle operating at its max, replace your cracked or worn out HVAC part with this superior URO component to optimize your HVAC system and stay cool or warm during...
      Designed to replace the original part in your HVAC systemHelps to optimize HVAC system to its proper performance
      $86.99
    • Calorstat® - Engine Cooling Fan Switch
      (0 reviews)
      # sp19599
      Engine Cooling Fan Switch by Calorstat®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $35.31
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of your...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. 5-Pin. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of your...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of your...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. 5-Pin. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of your...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of your...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of your...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of your...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. 5-Pin. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. 5-Pin. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. 5-Pin. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. 5-Pin. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure the heart of...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • Santech® - Relay
      (0 reviews)
      # mpn4371646243
      Relay by Santech®. For Auxiliary HVAC. Increase the life of your vehicle's engine by keeping your cooling system in top condition. Replace your faulty engine cooling component with this highly efficient replacement product and be sure...
      Made to keep your vehicle's engine running coolDesigned to maintain proper cooling level and prevent overheating
      $7.90
    • PSI® - Cooling Fan Pigtail
      (0 reviews)
      # mpn4499447031
      Cooling Fan Pigtail by PSI®. These pigtails allow for direct replacement of missing or damaged Coolant Fan Motor connectors on all LS1 style engines. Pigtails feature GM Delphi/Packard Connectors and Terminals as well as high...
      Designed for ultra high efficiencyEasy out-of-the-car access for an ancillary wiring
      $12.00
    • ACDelco® - GM Original Equipment™  Engine Cooling Fan Switch Connector
      (0 reviews)
      # sp114908
      GM Original Equipment™ Engine Cooling Fan Switch Connector by ACDelco®. Designed utilizing the latest technology, this product by ACDelco features premium quality and will perform better than advertised. Perfect for your vehicle and...
      Designed to deliver trouble-free, consistent performanceRight for your vehicle and lifestyle
      $13.83 - $26.55
    • ACDelco® - GM Original Equipment™ Auxiliary Engine Cooling Fan Relay
      (0 reviews)
      # sp16958
      GM Original Equipment™ Auxiliary Engine Cooling Fan Relay by ACDelco®. Designed utilizing the latest technology, this product by ACDelco features premium quality and will perform better than advertised. Perfect for your vehicle and...
      Designed to deliver trouble-free, consistent performanceRight for your vehicle and lifestyle
      $12.24 - $57.82




    The way many systems operate in your vehicle is dependent on the engine coolant temperature, making cooling system switches and sensors very important parts. These components provide an input to the engine control module (ECM), which in turn regulates fuel, ignition and other vehicle functions based on temperature and the input from other sensors. Coolant sensors and switches are threaded into coolant passages, where they are directly exposed to coolant for the most accurate temperature measurement in order to provide the engine control module with real time data.

    Coolant switches are used when a simple on/off signal is needed, as in the early fuel evaporation (EFE) system, which is used on some carbureted vehicles to heat the fuel mixture when the engine is cold to improve vaporization. In this system, a plate, with a heater grid under one or both carburetor barrels, is installed between the carburetor and the intake manifold. A temperature switch grounds the EFE circuit when the vehicle is cold and a relay supplies power to the heater grid. When the engine reaches a specified operating temperature, the switch opens, deactivating the relay and shutting off the heater grid.

    When a range of coolant temperature data is required, a coolant temperature sensor is needed. A common use for these data would be for a temperature gauge. Most coolant temperature sensors are thermistors, which change resistance according to temperature. Most of these are NTC (negative temperature coefficient) thermistors, which decrease resistance as temperature increases. The ECM sends a 5-volt reference voltage to the sensor and the sensor’s resistance reduces the voltage sent back to the computer. The temperature is calculated by the ECM based on the return voltage.

    The ECM uses temperature data from the coolant temperature sensor to: vary injector pulse width, increasing on-time for a richer mixture when the engine is cold, and decreasing on-time as the engine warms up; increase idle speed when the engine is cold, to prevent stalling; and turn the electric cooling fan on and off. In addition, coolant temperature information is critical because certain component function must only be enabled when the engine is warm. These include the EGR (exhaust gas recirculation) system, which would cause the engine to run rough and stall if exhaust gas was introduced to the intake when the engine is cold; the evaporative emissions control purge valve; and the transmission torque converter clutch.

    Some of the engine cooling system components, for example, a radiator fan, draw a high current from the power source. If you connect them directly or using a switch to the alternator or the battery, it may cause a short circuit, which can result in a fire or damage to the battery. To avoid such a turn of events, virtually all electric engine cooling system components are connected to the circuit through a relay. It is a small electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. This allows to power any energy-intensive devices without running the risk of damaging the battery or other vehicle components. Relays vary in size and construction, while their operating principle remains the same.

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    Cooling System Switches, Sensors & Relays Reviews

    Average rating:    4.5 - 23 reviews
    3 of 5
    Auxiliary Fan Control Unit
    Different brand shipped, used due to time problems OEM unit 6 pole, unit shipped 7 poles. Installed anyway. Seems to work only slow speed. No time to work through problems. Buyer beware.
    Posted by Julian (Savannah, GA) / September 6, 20181997 Mercedes C Class
    Was this review helpful for you? Yes
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