The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Trinary and 3 relay electric fan questions

Accelo · 06-19-2022, 07:27 PM

You question is clear as are the schematics. Must have taken you some time to post this. Great job BTW.

The Trinary Switch only grounds the relay so it can start one fan. This isn't really needed at all. You could use the Trinary switch to ground the Fan trigger #2 and it will bring in the high speed relay. I recommend running both fans when the Air is running. It will help keep the refrigerant pressures lower. I hid the relays behind the battery between the battery and the core support. This was a pain to make all the relay connections and still have it look appropriate.

I am using the same three relay set up for my fans. Works great with both fans running half speed till the other relay closed then it's full speed/voltage for both fans.

Diode are used to control the back EMF produced when the relay coil collapses. I didn't install any. I haven't had any issues so far but I really haven't driven in heat.

Cheers

06-19-2022, 07:27 PM	#2
Accelo Registered User Join Date: Mar 2015 Location: washington Posts: 2,176	Re: Trinary and 3 relay electric fan questions You question is clear as are the schematics. Must have taken you some time to post this. Great job BTW. The Trinary Switch only grounds the relay so it can start one fan. This isn't really needed at all. You could use the Trinary switch to ground the Fan trigger #2 and it will bring in the high speed relay. I recommend running both fans when the Air is running. It will help keep the refrigerant pressures lower. I hid the relays behind the battery between the battery and the core support. This was a pain to make all the relay connections and still have it look appropriate. I am using the same three relay set up for my fans. Works great with both fans running half speed till the other relay closed then it's full speed/voltage for both fans. Diode are used to control the back EMF produced when the relay coil collapses. I didn't install any. I haven't had any issues so far but I really haven't driven in heat. Cheers Last edited by Accelo; 06-19-2022 at 07:33 PM.