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Quick and not so dirty cooling fan switch

Old 05-07-2013, 02:46 PM
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Join Date: Mar 2012
Location: New York
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Cool Quick and not so dirty cooling fan switch

So instead of asking questions Im actually doing a write up :P

I decided to do look into this and do it to my car. It went pretty well considering my tendency to botch experiments.

The following write up is to turn on your fans when you want, it will not affect the normal function of your ECU and temp controlled fan switch nor will it cause a check engine light. This will only work with the ignition on so you dont have to worry about forgetting your fan is on and draining the battery. I do not recommend running your fans all the time. Do it at your own discretion. I recommend monitoring your cars temperatures when experimenting with this new feature. Note that constantly running your fans will produce a load on your car. I only saw a 2% increase in load at idle for my car. My approach for tests will be to sometimes run the fan at lights or when idling so reduce hood temps building up.

Side note: In the pursuit for cooling down your car, remember that too cool is not good. Cars have ideal operating temps since metal components in the engine expand with heat and engine oil reaches its ideal viscosity at certain temps. General rule of thumb is cooler for performance (advanced timing), hotter for fuel economy, all within a certain range.


So this is for the 5th gen accords. This may work on 4th and 6th gens similarly. Check your manual for details. If you have suggestions please feel free to comment.

The idea behind this is to complete the ground that the stock switch does when activated.


Switch of your choice for the 5volt current.
two different color wire, 16 AWG is fine (2 feet each)
Switch of your choice for the 5volt current.
splice connectors
electrical tape


Locate the fan control module in the car. It is a small black box hanging off the bracket behind the glove box. It should be labelled. You can flip the glove box downward or reach behind it to get to it.

Splice the green wire and run wire to the switch. You are leaving the circuit in together, just running a new wire into the circuit.
Green leads to the relays and the ECU. So if you get a CEL when doing this in ANOTHER car model, you may wanna find a way to bypass the ECU signal without interfering with normal fan function.

Splice the black wire in the same manner.
Black is the ground wire for the fan control module

Check to see if it works by turning on the ignition and switching the fans on. Recheck wiring if its not working. Turn the car on and check for a CEL with the fans on and off.

If all is good, wrap the wires up with electrical tape and run them to a location of your choice. As seen below I have mine by the OBD port. There was a convenient hole there. I just had to remove the panel and run it behind the stereo. Works like a charm.

See photos below for reference

Enjoy your small moment of control over your powerful machine, knowing your car is as cool as you look ;P

Attached Thumbnails Quick and not so dirty cooling fan switch-100_2411_zps9e214003.jpg   Quick and not so dirty cooling fan switch-100_2412_zps15bb52f1.jpg   Quick and not so dirty cooling fan switch-100_2413_zps92ff1690.jpg   Quick and not so dirty cooling fan switch-100_2414_zps282ef4a6.jpg   Quick and not so dirty cooling fan switch-previewofldquohondaaccordcoupe1994-1997servicemanualpdfrdquo_zps063bfc74.jpg  

Last edited by RobinsonRicer; 05-07-2013 at 02:50 PM.
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