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Full line of sensors for the Auto Cool Controllers


Copper Inline

If you have a PLASTIC radiator outflow port, you need use the inline copper sensor.   If you use the standard brass sensor on the plastic port, it will not absorb the correct amount of heat.  This will lead to a lower fan RPM that will let the radiator run hotter than normal.  


The  copper inline sensor can be ordered in 1.25 - 1.50 - 1.75 and 2 inch OD.   Measure your hose ID for the best copper inline sensor fit.  Be sure to email the diameter required.


One year warranty

on all sensors!







CALL: 562-367-3225​​

Standard Brass Sensor:

With each controller sold, we supply a standard brass sensor as standard.


However, if you order a Brass Plug or Copper

Inline Sensor, we do not include a Standard

Brass Sensor.  


The Standard Brass sensor is mounted on the OUTFLOW port under the rubber hose.    The sensor detects the outflow temperature and sets the fan RPM to keep the outflow port at a constant temperature.


If you have a radiator with plastic tanks and ports, you may want to order one of the copper inline sensor or the 3/8 inch brass plug sensor.


This sensor has a five foot twisted pair of 20 gauge wire that is connected to your Auto Cool Controller.   If you add wire to the sensor line, be sure to solder the splice to avoid open failures down the road.


If you order one of the Brass Plug Sensors, please email us the size you need.  1/8 - 1/4 or 3/8 inch.




A short YouTube video on the Brass Plug sensors from the Auto Cool Guy.  1/8 - 1/4 - 3/8 NPT

Be sure to use TEFLON tape on this type of sensor

for proper seal and no leaks!


We can make you a special sensor to order.  This one has an extra port for a drain.


Customer wanted to measure radiator inflow and outflow temperature with 1/2 inch ports on his radiator 


The Standard Brass Sensor will form fit all out flow ports sizes!  No need to tell us you want X size Standard Brass Sensor!!!!!!

We now have three Brass Plug Sensors.

1/8 inch - 1/4 inch  and 3/8 inch

Be sure you tell the Auto Cool Guy the

size of the sensor you need for your

radiator.  You can send an email or even a

phone call.   All three have the same price.


Mount the Brass Plug Sensor close to the

outflow port if you can - on the bottom of the



We supply extra twisted pair wire to extend

to your Auto Cool Controller.



The guys at Brand X controller company has you stick probes into your radiator core.  This can lead to leaks from vibration over time and miles.

Use only our sensor for Auto Cool, the brand X will not work!


Here is a simple trick to raise or lower the temperature range of your controller.  Running to COLD, install a resistor in SERIES with one lead of the sensor.  Start with 1000 ohms to about 5000 ohms, or use a small pot to set it.  Running to HOT,  install a small resistor across the sensor terminals.  Start with about 100,000 ohm and lower as needed.  Use a small pot to adjust this and and replace with a fixed resistor.   Call the Auto Cool Guy if you have any questions.

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