www.imoc.co.uk Forum Index
 AlbumAlbum CalendarCalendar FAQFAQ SearchSearch MemberlistMemberlist Legal NoticeLegal Notice IMOC 1/4 Mile1/4 Mile Table Knowledge BaseKnowledge Base   RegisterRegister 
 GarageCommittee GarageGarage  SubscriptionPremium Membership  ProfileProfile   Log in to check private messagesLog in to check private messages   Log inLog in 
Calendar 
[Mk2] [Turbo] Wiring engine lid fan.

 
Post new topic   Reply to topic       www.imoc.co.uk Forum Index -> MR2 MK2 1990 - 1999 NA & Turbo -> Electrical
View previous topic :: View next topic  
Author Message
kirk




Joined: 10 May 2015
Posts: 394

Feedback Score: 9



PostPosted: Mon Apr 03, 2017 8:34 pm    Post subject: [Mk2] [Turbo] Wiring engine lid fan. Reply with quote Reply with quote including images

Hi guys, I realise this has probably been covered a lot previously but I can't seem to find a proper answer.

Basically I want to run an engine lid fan to help cool the engine bay a bit better during the warmer months. My question is how can I wire it in to come on when my IC fan comes on? Is there a way to do it without the fan controller shutting it off due to too much load on the system?

I don't know if this is a problem or not but I wanted to check. Any info would be great. Please don't be mean [Laughing]
Back to top
User is offline 
alanmr2turbo




Joined: 28 Nov 2007
Posts: 2168
Location: Birmingham
Feedback Score: 10



PostPosted: Tue Apr 04, 2017 8:25 am    Post subject: Reply with quote Reply with quote including images

Why not just run the fans full time?
Isn't that the best way of sucking out engine bay heat?
Back to top
User is offline 
juliankv73
IMOC Moderator



Joined: 23 Jan 2005
Posts: 2619
Location: Bexley
Feedback Score: 108



PostPosted: Tue Apr 04, 2017 8:30 am    Post subject: Reply with quote Reply with quote including images

alanmr2turbo wrote:
Why not just run the fans full time?
Isn't that the best way of sucking out engine bay heat?


You could also wire it with a switch [Wink]
_________________
"If the milk turns out to be sour, I ain't the kinda pussy to drink it. Know what I mean?!"
Back to top
User is offline 
Pauln
Premium Member



Joined: 08 May 2006
Posts: 694
Location: Cardiff, South Wales
Feedback Score: 31

1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Tue Apr 04, 2017 11:24 am    Post subject: Reply with quote Reply with quote including images

Or run the new engine lid fan(s) via a separate power supply is switched on and off by a relay with the relay coil connected to the IC fan circuit. That way the additional load on the IC fan circuit should be minimal.

Paul
Back to top
User is offline 
Bear87
Premium Member



Joined: 28 Sep 2016
Posts: 224
Location: Essex
Feedback Score: 1

1992 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Tue Apr 04, 2017 7:07 pm    Post subject: Reply with quote Reply with quote including images

I agree with Paul (and he really knows his stuff) putting a relay in is the best way to ensure your not overloading the circuit. The fans draw a reasonably high current so a dedicated power supply of sufficient thickness of wire will increase reliability and lower risk of fire etc. Also don't forget the fuse the circuit! [Laughing]
_________________
Smoke me a kipper. I'll be back for breakfast.
1992 Rev 2 Turbo Super Red
1991 Rev 1 N/A Steel Mist Grey (daily)
Back to top
User is offline 
kirk




Joined: 10 May 2015
Posts: 394

Feedback Score: 9



PostPosted: Thu Apr 06, 2017 6:15 pm    Post subject: Reply with quote Reply with quote including images

Pauln wrote:
Or run the new engine lid fan(s) via a separate power supply is switched on and off by a relay with the relay coil connected to the IC fan circuit. That way the additional load on the IC fan circuit should be minimal.

Paul


As I'm pretty average at wiring how would I go about doing that? [Mr. Green]
Back to top
User is offline 
Pauln
Premium Member



Joined: 08 May 2006
Posts: 694
Location: Cardiff, South Wales
Feedback Score: 31

1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Fri Apr 07, 2017 2:04 pm    Post subject: Reply with quote Reply with quote including images

First you need to check what current your new engine lid fan(s) are going to draw. Look for a label on the fans or ask the seller, but as an example a single 240mm fan could draw as much as 8amps.

Once you know the current draw you can purchase an inline fuse holder, relay and cable from the likes of Halfords or Maplins of suitable for that current.

Here's a rough sketch of how to wire your new fan(s) up.



Automotive relays usually come with the terminals numbered 85 and 86 for the relay coil and 30 and 87 for the supply you want the relay to switch.

You should then pickup a new supply and feed this via a suitable fuse to terminal 30 on the relay.

Then tap into the existing two wires that connect to the IC fan and run additional cables to terminals 85 and 86 on the relay.

When the IC fan comes on it will then power the relay coil which will in turn switch on the independent supply to your new engine lid fan(s).

Hope that all makes sense.

Paul
Back to top
User is offline 
kirk




Joined: 10 May 2015
Posts: 394

Feedback Score: 9



PostPosted: Sat Apr 08, 2017 4:21 pm    Post subject: Reply with quote Reply with quote including images

The fan I intend on running is has a 7 amp draw.

Would the 12v supply from the fuse box be suitable? Granted it would be live all the time rather than a switched 12v but it's probably the closest thing without tapping into other wires.

I'm guessing I just need a bosch type 4 pin relay as well?
Back to top
User is offline 
Pauln
Premium Member



Joined: 08 May 2006
Posts: 694
Location: Cardiff, South Wales
Feedback Score: 31

1993 Toyota MR2 Mk2 Turbo Rev2

PostPosted: Sat Apr 08, 2017 5:55 pm    Post subject: Reply with quote Reply with quote including images

Bosch type 4 pin relay should be fine, just make sure it's rated t at least 10 amps as the starting current on a motor is often a bit higher than the running current.

It's a fairly substantial looking feed to the engine compartment fuse box, but I don't know if that's straight feed from the battery. It should be OK, but if it's a fused supply, I've no idea how much spare capacity there is.

As no current will be drawn by your new fan unless the IC fan is running it shouldn't really be an issue using a non ignition switched supply.

Paul
Back to top
User is offline 
kirk




Joined: 10 May 2015
Posts: 394

Feedback Score: 9



PostPosted: Sun Apr 09, 2017 4:49 pm    Post subject: Reply with quote Reply with quote including images

Thanks a lot Paul [thumleft]
Back to top
User is offline 
Display posts from previous:   
Post new topic   Reply to topic       www.imoc.co.uk Forum Index -> MR2 MK2 1990 - 1999 NA & Turbo -> Electrical All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group