Change cooling fan temperature switch points - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Bernithebest · 01-19-2016, 06:33 PM

I see a lot of discussion about managing engine temperatures. To me it seems that many issues would be resolved if the fans would just kick in a little earlier. 160 degree thermostats is no help in stop and go traffic if the fans kick in at the same high temperature.
Has anyone tried to change the fan switch points in the engine controller - DME?
Seems like this should be no more difficult than changing the redline rmp etc.

spongebob · 01-24-2016, 04:46 AM

I have asked the same here before without success. I guess the solution is to re- program the computer. Noticed that with AC on, engine temp is generally lower when driving at lower speed due to the fans in low speed. Not perfect but helps a bit.

Chuck W. · 01-24-2016, 06:36 AM

I think a better way would be to have a manual switch to activate the fan.

Take a look at post number two by Qmulus in the below thread. I have considering doing this numerous times..... if I could only identify where to "In a convenient place cut the yellow/gray wire from DME to the high speed fan relays".

Manual radiator fan

lkchris · 01-24-2016, 06:53 AM

What issues?

Solutions looking for problems seems to me.

thstone · 01-24-2016, 10:02 AM

Quote:

Originally Posted by lkchris

What issues? Solutions looking for problems seems to me.

The perceived issue is that the ECU allows the temp to get too high before turning on the radiator fans. Heat is the enemy. Higher temps = reduced oil performance = greater engine wear = shorter engine life. At least that is the theory and concern. As the OP stated, he would like to be able to change the temp setting or have a way to manually engage the fans at a lower temp.

To the best of my knowledge, the temp settings can't be reprogrammed in the ECU. Thus, others have installed a manual switch.

I am testing out a manual switch for the engine bay fan (passenger side rear fender) this afternoon and if it works, I'll post up the details for that one.

thstone · 01-24-2016, 10:10 AM

Quote:

Originally Posted by Chuck W.

I have considering doing this numerous times..... if I could only identify where to "In a convenient place cut the yellow/gray wire from DME to the high speed fan relays".

I would do this under the dash where the relays are located. Just find the trigger wire going to the relay and then back up and find a good place in the wire harness to splice in.

jaykay · 01-24-2016, 10:28 AM

Nice mod......really want this for dealing with being stuck in traffic .....I imagine having having the fans running while moving at speed would improve cooling air flow as well.

Anybody have a idea which stock switch might give a SPST configuration? Maybe wiring diagrams show this. It would be nice to package this switch in the batwing andlook stock.....maybe a repurposed seat heater switch

particlewave · 01-24-2016, 11:17 AM

Jay - the OEM switches are all momentary, meaning only active while being pressed. You'd have to hold it.

That, or get a bit more complex with the setup.

jaykay · 01-24-2016, 11:28 AM

Quote:

Originally Posted by particlewave

Jay - the OEM switches are all momentary, meaning only active while being pressed. You'd have to hold it.

That, or get a bit more complex with the setup.

Ugh....a latching relay set-up. I guess I am going to end up with a row of toggles.......which I quite like. Un fortunately they don't fit well with the style of the interior.

Meir · 01-24-2016, 06:57 PM

Quote:

Originally Posted by jaykay

Ugh....a latching relay set-up. I guess I am going to end up with a row of toggles.......which I quite like. Un fortunately they don't fit well with the style of the interior.

Or, you can use a step relay.

Meir · 01-24-2016, 07:02 PM

Quote:

Originally Posted by Chuck W.

I think a better way would be to have a manual switch to activate the fan.

Take a look at post number two by Qmulus in the below thread. I have considering doing this numerous times..... if I could only identify where to "In a convenient place cut the yellow/gray wire from DME to the high speed fan relays".

Manual radiator fan

If you are looking for more "fan power" why not jumper the low speed relay wires with the high speed relay? in that case, the fans will always kick in on high.

jb92563 · 01-24-2016, 08:44 PM

Has anyone considered the OBDII connector and sending the right signal to the computer.

The Durametric units can turn the fans on and off and set the fan speed. Perhaps this is another OBDII Arduino Hack candidate.

jacabean · 01-25-2016, 03:33 PM

just turn your ac on . thats what i do in the heat and traffic .

jaykay · 08-21-2020, 09:41 PM

Quote:

Originally Posted by jaykay

Ugh....a latching relay set-up. I guess I am going to end up with a row of toggles.......which I quite like. Un fortunately they don't fit well with the style of the interior.

Have any found a schematic of the seat heater switches? I would like to be able to use it to activate the radiator fans with one position and the engine bay with the other. One switch to do both functions.

jaykay · 08-21-2020, 09:47 PM

Quote:

Originally Posted by Meir

If you are looking for more "fan power" why not jumper the low speed relay wires with the high speed relay? in that case, the fans will always kick in on high.

So doing this would negate the need for installing manual switches as triggering the Ac on will now put the fans on high right of the bat? I can't picture the jumper arrangement as yet or downsides......it's late though!

jaykay · 08-21-2020, 09:53 PM

Quote:

Originally Posted by Meir

Or, you can use a step relay.

I am not familiar with these but perhaps this would have the added capability of running the engine compartment fan as well.....less relays

maytag · 08-21-2020, 11:06 PM

Quote:

Originally Posted by jaykay

Have any found a schematic of the seat heater switches? I would like to be able to use it to activate the radiator fans with one position and the engine bay with the other. One switch to do both functions.

I installed a very simple 4- channel remote / relay setup, with a 4- button key fob. Button A toggles my exhaust bypass valves. Button B is blank. C toggles the engine bay purge fan. Button D toggles the high speed radiator fans. When C and D are toggled "off" they work per OEM.

I did this because my car sees a lot of track time in 95d+ ambient temperatures.

I'll admit that I think i need some indicator LED's somewhere since I can't always hear when they're on, if the engine is running.

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jaykay · 08-22-2020, 08:49 AM

Sounds like a great set up any details on the equipment you used? I have seen many remote exhaust valve actuators but not any remote controlled contacts

maytag · 08-22-2020, 12:54 PM

Quote:

Originally Posted by jaykay

Sounds like a great set up any details on the equipment you used? I have seen many remote exhaust valve actuators but not any remote controlled contacts

This is the one I used.
https://www.amazon.com/dp/B07MTYGJHQ/ref=cm_sw_r_cp_apa_i_kxyqFbH272GHH

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