Dual fan woes
 

Hello, while I am waiting on some parts to get my car back on the road, I'd like to squash this issue I've been having with my fans.

I've got the dual fan setup, when I turn the car into the "on" position, without starting the car, the fan on the passenger side automatically comes on.

Now it is me belief that both fans are "switched" and one should come on when the ECM requires it, and the other one comes on at like 231 or something like that.

I've got a picture of a suspicious connection, but I can't figure out what actually is going on.

I've got the shop manual for my year, with the electrical diagrams, but it's not really one of my strengths.

Any help out there?
https://cimg2.ibsrv.net/gimg/www.thi...58b1ea3114.jpg
https://cimg4.ibsrv.net/gimg/www.thi...621e2de17a.jpg

Re: Dual fan woes
 

Where does the brownish grey wire come from? What color wires does the orange wire hook too?
My guess is the brownish wire is grounded somewhere and they spliced the orange wire to complete the switch at the relay. Like you said relays work by ecm the temperature switch in the head (ground). The ecm supplies a ground as needed to run the fan(s). The AC has a grey wire that also ties into the fan aux fan switch wire. The AC grounds the circuit and run the fan by going through the green/white wire.

I using black and white diagrams but color makes more sense of it.

Re: Dual fan woes
 

Hi guys,

I have a similar situation. My 92 Z28 used to get hot a lot until I decided to by-pass the ECM and hook up my own fan switches and relays. I do not have issues anymore but the red power wire for my fans is hooked directly to the battery. What this means is when I shut the car off the fans continue to run until the temp is below what the fan switch is rated at then the fans shut off on their own. My question is where can I find a 12 volt source under the hood that goes on and off with the key?

Thank you

Re: Dual fan woes
 

The passenger fan is triggered by a temperature sender on the passenger cylinder head. It is also triggered by the A.C. being activated by a pressure switch. Have you checked there?

Re: Dual fan woes
 

Mine did this too when I bought it. After I replaced the temperature switch on the pass side mentioned above by thainglo it worked normally. Maybe see if unplugging it stops it? To rule out that it's wired/shorted to be on all the time. It's the one down by the knock sensor.
Side note: when you're down there the plastic on the knock sensor connector is probably going to break on you. If you need to replace it, you can get the connector and simply de-pin & re-pin to avoid soldering/crimping & cutting the wire.