Mike8675309
Registered User
As many know, the issue with the two speed cooling fan on our cars is that the low speed winding must not be energized while the high speed one is.
Thus if you cut #14 and your car still gets hot, it's possible the EEC will turn on the high speed fan while you've got the low speed fan forced on.
This means you'll need to take control of the high speed as well and maybe do all this manual with switches.
There's a good diagram going around that shows how to wire this with thermostatic switches and a couple relays. But if all you want to do is make sure the low speed is off when the high speed comes on, you can do this:
In the picture below you'll see that #14 is cut and a jumper has been run from the IRCM side of #14 to a 3M tap into line #17. Thus when the EEC-IV "grounds" #17 to turn on the high speed fan, this ground will shut down the low speed winding. The once the high speed fan goes off, it'll start the low speed fan again.
Thus if you cut #14 and your car still gets hot, it's possible the EEC will turn on the high speed fan while you've got the low speed fan forced on.
This means you'll need to take control of the high speed as well and maybe do all this manual with switches.
There's a good diagram going around that shows how to wire this with thermostatic switches and a couple relays. But if all you want to do is make sure the low speed is off when the high speed comes on, you can do this:
In the picture below you'll see that #14 is cut and a jumper has been run from the IRCM side of #14 to a 3M tap into line #17. Thus when the EEC-IV "grounds" #17 to turn on the high speed fan, this ground will shut down the low speed winding. The once the high speed fan goes off, it'll start the low speed fan again.