Please visit the Club's website https://www.dloc.org.uk/ to join. Visit https://www.dloc.org.uk/adhoc to DONATE towards the cost of the forum.
Please don't post someone's email address to avoid it being harvested by spambots and it's against GDPR regulations.
Always look at "ACTIVE TOPICS" to see all posts in date & time order as they are sometimes moved; or look at "Your Posts".
Please add Reg. nrs. when posting a photo or anything about a car as this will help searches. Don't add punctuation next to nr. as this negates search.
CHANGED YOUR EMAIL ADDRESS since registering?, click your username and check your address in User Control Panel, Profile, Account Settings.
If you want help to register, use "contact us" at page bottom for help.

Wiring electric fan.

Post Reply
Flinty
Posts: 90
Joined: Mon Sep 24, 2018 7:34 pm
Location: Scarborough

Wiring electric fan.

Post by Flinty »

My SP has an electric cooling fan and runs after the engine has stopped for sometimes quite a few minutes.
It also often starts well after the engine has been switched off causing alarm to some people who are close to the car. I wonder whether to switch it via a relay through the ignition switch so that it only runs when the engine is running,
Any wise men have any thoughts.

Steve.

Bill Swizz
Posts: 48
Joined: Thu Aug 13, 2020 9:22 am
Location: Basel, Switzerland

Re: Wiring electric fan.

Post by Bill Swizz »

Does your car also have an electric water pump? If it does the run on after stopping is useful and normal as the water pump is probably running on too.
Without this it is only able to cool the water in the radiator so won't provide much if any cooling to the rest of the system as the water is not circulating, though there may be some small effect due to heat soak and conduction as well as pushing cooler air into the engine bay.
I had EWP and fan run on in my race lotus Elise and it was good in the pits after a run.

Paul Edginton
Posts: 48
Joined: Sun Feb 14, 2016 1:56 am

Re: Wiring electric fan.

Post by Paul Edginton »

Hi Steve,
I have the same situation on my V8 saloon but I do not consider it to be a problem.
My understanding is that this is caused by "heat soak" when the hot coolent rises to the top of the radiator turning on the fan. via the thermoswitch.
An electric water pump setup with the electric fan would be the ultimate set up in my opinion as you would get faster warmup and cooling down. The electric pump would be more efficent than a mechanical one also. The whole system would be controled electronically.
Paul

Flinty
Posts: 90
Joined: Mon Sep 24, 2018 7:34 pm
Location: Scarborough

Re: Wiring electric fan.

Post by Flinty »

Thanks Bill and Paul;.

i do not have an electric pump just the fan and I was thinking that in standard form the fan and water pump would stop when the engine stopped so why do I have the electric fan running after the engine stopped.

Steve.

Bill Swizz
Posts: 48
Joined: Thu Aug 13, 2020 9:22 am
Location: Basel, Switzerland

Re: Wiring electric fan.

Post by Bill Swizz »

Steve,

As Paul says this is probably caused by heatsoak reaching the sensor after the engine is stopped. If the fan is controlled by an electronic programmable controller this may be due to that rather than heat soak, but heat soak seems more likely.
I'd add a normal 4 pin relay into the circuit powering the fan controller with the new relay controlled by the ignition switch.
Connect relay terminal 86 to the +ve from the ignition.
Connect relay terminal 85 to ground.
Connect terminals 87 and 30 into the fan controller circuit.

It should do no harm to leave it as it is with no ignition switching, except that you will be making your battery do a bit more work which might be an issue restarting if your battery is not in good condition or was low on charge when you turned the engine off and I guess there is a small fire risk from lots of unnecessary switching on and off of the fan circuit and earlier failure of the switch itself.

Bill

silverdart
Posts: 285
Joined: Sat Feb 13, 2016 10:49 am
Location: West Midlands

Re: Wiring electric fan.

Post by silverdart »

Hi, My fan is set up as you suggest, ie. through the ignition. I would have thought this is the best way to do it as you would not normally want to cool the engine quickly if you were stop starting on short journeys.

Dave.

Post Reply