2 speed contour fan wiring

Moderator: Mod Squad

69stang_250
Registered User
Posts: 467
Joined: Thu Aug 13, 2015 1:47 pm
Location: Covington, Louisiana
Contact:

2 speed contour fan wiring

Post #1 by 69stang_250 » Fri Jul 22, 2016 8:21 pm

I have done some research and this is confusing the heck out of me.

Anyone have a good wiring diagram for installing dual 2 speed electric fans?

Is there a single switch that will allow me to run both high and low speeds without using a toggle or one?

Is there a descent 2 speed controller out there that will last?

I have read mixed reviews on the ones I have found and would rather build my own than chance it.

Thanks for the help y'all.
69 mustang coupe, 250 .030 over, forged pistons, port & polished CI AL head 54cc's 10.25CR, 280/280 Clay smith cam 1 degree advanced, 1.6 adjustable rockers,
Re curved DSII, MSD AL6, CI Intake, FITech 400HP fuel injection. T5 trans, 8" rearend w/3.80 gears, Eaton trutrack.

thesameguy
Registered User
Posts: 687
Joined: Thu Jan 27, 2011 5:34 pm

Re: 2 speed contour fan wiring

Post #2 by thesameguy » Tue Jul 26, 2016 2:25 pm

FML. I had this all types out and somehow erased what I've written.

What you want is a dual thermoswitch. Easy junkyardable ones are from most BMWs from the '90s or a mid '80s VW Jetta or Golf or a '90s Audi with the inline five. IMHO, the BMW option is the easier one as the VAG options have a huge M22 thread. I guess either way you're welding a nut somewhere. :) You need either a pair of relays (one for each speed) or easier/cheaper is the fan relay from a '90s FWD Volvo. Check this:

http://www.nastyz28.com/forum/showthread.php?t=200028

You can also go aftermarket for the system - Hayden, Derale, and others all make 2-speed capable controllers, but you'll spend a fair amount of money. The upside is these kits use sensors/probes that are far easier to fit than the M14 (BMW) or M22 (VAG) sensors - typically 1/8" or 1/4" NPT. Also - IMHO - the aftermarket adjustable ones will let you run higher temperatures. The BMW switch is 180/195 (IIRC) which might be too low for an old iron engine. You'll probably be giving up some fuel economy and making some extra smog running that cold. You can get around that to some degree by creative location of the sensor (cold side of the radiator, etc.), but the adjustable ones do let you dial in the temp a lot more easily. Upside to the BMW/Volvo solution is that they're factory parts and will probably dramatically outlast anything aftermarket. I have a Derale adjustable controller in my XR4Ti and it's eaten two of them over the last eight years. I'm expecting the third one to die any minute now. :(
Last edited by thesameguy on Tue Jul 26, 2016 7:48 pm, edited 3 times in total.

69stang_250
Registered User
Posts: 467
Joined: Thu Aug 13, 2015 1:47 pm
Location: Covington, Louisiana
Contact:

Re: 2 speed contour fan wiring

Post #3 by 69stang_250 » Tue Jul 26, 2016 2:53 pm

I found an easy wiring diagram for the Taurus 2 speed fan and plan on adjusting it for dual fans using the VW switch.
I will use a hose adaptor and tap it for the switch. I've found most put these near the top radiator. I'm not sure where the best place to put the switch is though.

Right now I am waiting on the diodes to show up so I can start the wiring.

This is the way I plan on wiring the fan up.
You do not have the required permissions to view the files attached to this post.
69 mustang coupe, 250 .030 over, forged pistons, port & polished CI AL head 54cc's 10.25CR, 280/280 Clay smith cam 1 degree advanced, 1.6 adjustable rockers,
Re curved DSII, MSD AL6, CI Intake, FITech 400HP fuel injection. T5 trans, 8" rearend w/3.80 gears, Eaton trutrack.

thesameguy
Registered User
Posts: 687
Joined: Thu Jan 27, 2011 5:34 pm

Re: 2 speed contour fan wiring

Post #4 by thesameguy » Tue Jul 26, 2016 7:40 pm

Wow, that seems unnecessarily complex. You only need two SPDT relays, using three SPST relays is I guess a solution, but it seems pretty clumsy to me. Also, putting the diodes in the current path to the fans results in needing some serious diodes and possible loss in forward bias mode. Honestly, I would not pursue this. I would really recommend just finding a Volvo relay, either in a junkyard or off ebay for $20. Failing that, here is the simpler approach with two SPDT relays:

Image

SPDT relays have two outputs, one that is always connected and one that is switched. In this configuration Relay 1's resting position goes nowhere (87a). When it's energized by the ignition switch being turned on AND the low temp switch triggered, it switches, connecting your battery to output 87b.

Relay 2's resting position is connected to the low speed fan. So, when Relay 1 is pulled down, Relay 2 immediately passes battery voltage to the low speed fan. When the hi temp switch is triggered, it switches Relay 2 and the high speed fan is energized.

It's a lot less complex and a lot less wiring. not to mention eliminating two giant diodes.

Note that this configuration does not account for AC as your diagram did. If you want the AC to turn the fan on, you would connect the AC switch to terminal 85 on Relay 1, same place as the ignition switch goes. You will want a diode on the AC switch leg to block voltage going directly from the ignition switch to the AC system, bypassing the AC switch. But this only need be a tiny diode to block a few mw of power.

Amazon has 5-packs of SPDT relays for $14, complete with connectors: https://www.amazon.com/Pack-EPAuto-Rela ... SPDT+relay

They are 30a rated, and should be enough to run the Contour fans.


Forgot: You are going to want to fuse this - I would recommend two fuses, one each at Relay 2 87a and 87b. But, you could also cheat and put one fuse between the battery and Relay 1 30. The two fuse scenario is preferable, placing the fuse as near the load as possible and might allow one speed of the fan to run even if the other fails. One fuse is one point of failure, and runs the risk of cooking the relays.

Who is online

Users browsing this forum: No registered users and 3 guests