2G A/C switch to turn on fans gone wrong

[chrisman287]

When I bought the car both slim fans were connected to a toggle switch along with the wideband, boost and voltmeter gauges on the a-pillar. I cleaned all that wiring up and now have the gauges come on with the ignition. I was going to wire the fans to a cleaner push button style toggle but then I found this video:

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So I gave that a try but I don’t think my ECU controls the fans at all. It looks like they’re wired directly to the toggle (no stock fan plugs or plug on temp switch at thermostat). So since my toggle had constant power from the fuse box (which is in my dash where the passenger side airbag goes) I added an inline fuse on the power wire, hooked that to the white wire (which was supposed to go to pin 20 on the ECU) and had the blue wire connected to the wires that came into the dash for the fans. It worked for all of 4 seconds before the switch smoked up. LED on the switch still lights up when pressed but the fans don’t come on anymore.

Should I have used a relay instead of wiring it directly to the A/C switch?

 

[chrisman287]

Also, is the switch on the dash replaceable by itself?

 

[randman2011]

So wow, that's all kinds of messed up. I will never understand why people change the factory fan setup, because it works WELL.

Yes, the AC switch can be replaced separately from the rest of the HVAC controls. There are two styles. The early (95 only?) style with green and amber LEDs and three modes, and the later style with only a green LED and two modes. They will look the same when unplugged but I suspect the connector is different? I've never pulled them out myself to inspect.

 

[99dsmer4g63]

I followed Jason’s video and my system works flawlessly. This is in a 99 and the fans wouldn’t work with the ecu. Everything checked out and I applied ground to pin 20 and the fans kicked on but won’t on their own. Something I need to look into I guess. My button is the green only led button. I can snap a picture of it when I’m home and see if the connectors are different for you.

-Daniel

 

[chrisman287]

So wow, that's all kinds of messed up. I will never understand why people change the factory fan setup, because it works WELL.

Yes, the AC switch can be replaced separately from the rest of the HVAC controls. There are two styles. The early (95 only?) style with green and amber LEDs and three modes, and the later style with only a green LED and two modes. They will look the same when unplugged but I suspect the connector is different? I've never pulled them out myself to inspect.

This is a 95 so it does have the three mode switch. Thanks for that info I wasn’t aware of that.

 

[chrisman287]

I followed Jason’s video and my system works flawlessly. This is in a 99 and the fans wouldn’t work with the ecu. Everything checked out and I applied ground to pin 20 and the fans kicked on but won’t on their own. Something I need to look into I guess. My button is the green only led button. I can snap a picture of it when I’m home and see if the connectors are different for you.

-Daniel

If you could get a picture of the connector that would be great. Thank you.

 

[99dsmer4g63]

Here is a picture of the 99 connector. Second picture is the first picture orientation flipped straight up. I have my blue and white wires tapped for the fan control.

-Daniel

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