Fan Problems...
Thread Starter
Burning Brakes
Joined: Apr 2000
Posts: 959
Likes: 1
From: Lemoore CA
Fan Problems...
Im confused.... I read the tech tips, and tried to wire my own auto fan switch. For starters I have in the past occasionally blown the GAUGES fuse, although I havnt driven the car for quite some time. Now when I looked for a green/white wire there wasnt one, so I checked the Elctrical Diagrams in my 90 Vettes manuals.... It seems as though the pink/black wire is the wire that is ignition-hot so I tried to ground that. I had the relay disconnected and tried to ground it... Nothing So I connected the relay, then tapped into the wire and ground the pink/black connection with the relay hooked up. This caused that gauges fuse to blow.... Grounding at the battery.... So I tried a second time, same thing..... I them tried to pull engine codes to get the fans to turn on (after changing the fuse of course) and both fans fired right up.... Whats the deal??? Im sooo confused. Im thinking maybe I have a bad relay, but I dont see how the fans would then turn on with the ALDL grounded.
Any help will be greatly appreciated....
Paul
Any help will be greatly appreciated....
Paul
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Fan Problems... (Nomar116)
I believe your '90 Vette has two fans side-by-side; my '88 has a main fan behind the radiator and a small aux fan in front of it. In your case both fans are controlled by the ECM.
Indeed the AMP GAUGES fuse supplies +12Vdc to the fan relays control terminals through the pnk/blk wires. Your ECM pulls the main fan relay control to ground through the grn/wht wire and the secondary fan relay through the blu/wht wire.
Other than coolant temp, and the diagnostic ALDL the ECM will turn on the fan(s) when the NC A/C pressure switch opens. If you disconnect the grn/wht wire from this switch and start the engine, the ECM should turn on at least the main fan.
To turn your fans on manually, select a DPST switch. Splice a wire into the grn/wht wire going to the input of the main fan relay and run it to one side of the manual switch. Splice a wire into the blu/wht wire going to the input of the secondary fan relay and run it to the other side of the manual switch. Then connect the other two switch pole pairs to a wire that runs to ground.
Indeed the AMP GAUGES fuse supplies +12Vdc to the fan relays control terminals through the pnk/blk wires. Your ECM pulls the main fan relay control to ground through the grn/wht wire and the secondary fan relay through the blu/wht wire.
Other than coolant temp, and the diagnostic ALDL the ECM will turn on the fan(s) when the NC A/C pressure switch opens. If you disconnect the grn/wht wire from this switch and start the engine, the ECM should turn on at least the main fan.
To turn your fans on manually, select a DPST switch. Splice a wire into the grn/wht wire going to the input of the main fan relay and run it to one side of the manual switch. Splice a wire into the blu/wht wire going to the input of the secondary fan relay and run it to the other side of the manual switch. Then connect the other two switch pole pairs to a wire that runs to ground.
Thread Starter
Burning Brakes
Joined: Apr 2000
Posts: 959
Likes: 1
From: Lemoore CA
Re: Fan Problems... (65Z01)
God that was exactly the explanation I needed.... I cant thank you enough.... Ive been having blown fuse problems for a very very long time now, and although this wont cure them, I wont be running hot anymore (especially on the new motor) I did however buy the wrong switch I believe, it is a simple three position toggle, I believe one says ignition power, one says something to the effect of always hot and one is for the ground... Not exactly good for something to give me the choice to run just one or both fans.... If thats what your getting at with running both primary and secondary seperately. Im not at all an electrician so this isnt my strong suit here I was planning on taping into the wires from the secondary and primary, connecting them TOGETHER, running one to the switch with another wire to ground powering both simultaneosly Should I avoid this method? As for the coloration, according to my manuals and I guess my poor eyes (only 17 too....) One wire looks blue with white while one really really looks light blue with white not green at all.... 
I guess thats the problem :rolleyes: The manual even mentions a light blue wire.... So anyway Ill give that method a try let me know about the switch selection though.
Paul
I guess thats the problem :rolleyes: The manual even mentions a light blue wire.... So anyway Ill give that method a try let me know about the switch selection though.Paul
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Re: Fan Problems... (Nomar116)
Each fan relay coil goes to 12 volts. The other coil wire on each fan relay is grounded by a fan controller (ECM or thermostatic switch in the block). You were blowing fuses because you were grounding the 12 v wire. You need to ground the relay coil with the green/white and blue/white wire . Ozvette has good advice by grounding both fan relays separately with a dpdt switch. This way both fans are on allowing for maximum cooling. It sounds like you have a green color blindedness. Get tested and find out for sure .
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Fan Problems... (Nomar116)
The reason I suggested a DPST (or you could use a DPDT) switch is to keep the relay control wires separated. That way when the switch is in the open (Off) position the ECM will control each fan as before. Yet when you close the switch it will ground both fan realy inputs, turning on both fans.
Thread Starter
Burning Brakes
Joined: Apr 2000
Posts: 959
Likes: 1
From: Lemoore CA
Re: Fan Problems... (65Z01)
That makes alot of sense ALSO.... So when I go to radio shack I ask for a DPST switch ??? And can I get a pretty one that lights up red light the one Advanced auto parts sold me :p:
