Thermo fan wiring - series/parallel

[nick88]

Hi guys, im trying to figure out how to wire up my thermo fans in my car, so that on 'Low speed' both fans are wired in series so they are getting 6v each, and when high speed is activated(via computer or manual overide switch) they are wired in parallel and recieve 12v each.

I think ive worked it out, just looking for clarification and/or possible other ways to wire it with more/fewer relays

Any help appreciated

Heres my diag so far...

Please excuse the crude drawing and my handwriting! haha
also just incase you cant read my writing, when the Low speed is active, only it has power. But when High speed is active both Low/High wires have power, i can easily change this to just Low - Low, High - High if need be to make it easier, and car it is for is a VS caprice

 

[axemurderer101]

the fans in series is still 12 volts lol

 

[nick88]

Electrical Circuits - Series and Parallel Circuits, Ohms Law

Read point 2

 

[wamboin23]

try this. uses 2 change over, one standard.



the au falcons use a setup the same, with 3 relays to control there fans.

 

[nick88]

when you say change over, do you just mean ones that have 87a terminal?

 

[wamboin23]

thats them.

 

[PanthaVS]

I believe this would work... if you could get your hands on a 12V / 30A rated DPDT relay.

When Both inputs recieve a + (fans are in parallel).
When Only the standard relay input has a + (Fans are in series).

 

[nick88]

try this. uses 2 change over, one standard.

View attachment 104623

the au falcons use a setup the same, with 3 relays to control there fans.

wamboin23 - Thanks man i wired it as per your diag and works perfectly!
thanks again