Question: manual fan Switch

[jamison]

I have a 1990 with the 2 fan relays located on the driver side radiator shroud. i want to wire up a manual switch to turn both fans on and off with out having to turn on the ignition key this way when i take the car to the track i can have it cool down between runs. but i also need it to have the fan temperature switch working properly when just cruising the town. i have seen kits online from mid america, but im not sure if they work with the ignition off. plus i have already bought a switch and have plenty of wire. i just don't know how to wire it up. that where i could use your guises help.

thanks jamison

 

[Red Vette]

I have a 1990 with the 2 fan relays located on the driver side radiator shroud. i want to wire up a manual switch to turn both fans on and off with out having to turn on the ignition key this way when i take the car to the track i can have it cool down between runs. but i also need it to have the fan temperature switch working properly when just cruising the town. i have seen kits online from mid america, but im not sure if they work with the ignition off. plus i have already bought a switch and have plenty of wire. i just don't know how to wire it up. that where i could use your guises help.

thanks jamison

I had purchased the MAMW fan switch and installed it on my 94 vert. The fan switch came with directions, and you could look at their catalog to see if they include the directions with the description. Basically, one attaches two of the three wires to the controllers on the side of the radiator shroud, and the third to the ground. When the switch is turned on, it grounds the fans and they turn on. The fans do not run with the ignition off with the MAMW switch, so you would have to have some hookup directly to a battery source of power, by-passing the ignition switch. I went thru the firewall and had the switch inside the cabin, positioned between the knee pad under the steering wheel and the vertical carpeting on the console near the radio. That way I did not have to drill a hole or mount some kind of device to house the switch. Worked fine for me and brought down the temps whenever I felt is was getting too hot. I would watch the coolant temp drop by initiating the gauge readings on the DIC. Hope this helps.
Barrett

 

[G Winter]

A double pole single throw switch. Wire one side of the switch to the green ( should check FSM to be sure,ECM grounds coils on the relays to turn on fans) wire on each relay. Wire the other connection of each pole to ground.
When you turn on the switch it grounds the relay coils turning on the fans. Wiring this way insures that both fans don't come on when the ECM only calls for one. To run them with the ignition off you would need another switch to supply power to the relay-fan power side. You could do this with a timer also so that you wouldn't have to be there to turn them off.

Glenn

 

[vetteoz]

when i take the car to the track i can have it cool down between runs.

Be aware this only cools the water in the radiator , not the engine.
You need a elec water pump to circulate the coolant and gain full benefit of running fans with engine off like the pro racers.
Consider the mentioned timer essential; forget and walk away , your battery will be flat fast with both fans running

 

[jamison]

hey guys thanks for replying so fast. i decided to just wire it up with the ignition on. i loaded the instructions from mid america and they say to connect to the green with white stripe wire on the fan relays, but when i look at mine there is no green wires. but in the picture they show to attach it to the F slot of the fan relay plug. in my primary there is a dark blue with white stripe and in my secondary there is a light blue with black stripe. so should i attach to the F slot as it sais or do you think it might be wired different?

 

[G Winter]

I find it sort of strange that two 90s would have diff color wires. Mine are green with white stripe, but the relay markings don't lie. Mine has red wire to one of the contact terminals and to one side of the coil.The other side of the contact goes to the fan, should be a fairly heavy wire. If you can see the top of the relay there is a pictorial diagram on it.

Glenn

 

[Schrade]

I find it sort of strange that two 90s would have diff color wires. Mine are green with white stripe, but the relay markings don't lie. Mine has red wire to one of the contact terminals and to one side of the coil.The other side of the contact goes to the fan, should be a fairly heavy wire. If you can see the top of the relay there is a pictorial diagram on it.

Glenn

'94 might also have different color wires somewhere in the headlight circuit. I found a mistake in the '94 FSM for wiring color (unless 2 colors were used).

OP; there's an FSM fan relay schematic with detailed comments and pics in this thread.

 

[gw962]

I just checked the electrical supplement for my 90 and it shows light blue/ black wires for both relay coils, that are grounded by the ECM. I then checked the car and have a dark blue/white and light blue/black.
So much for accuracy in a FSM...

 

[nelson84]

You could wire it to the windshield wiper, when the key is turned on your fan will run all the time, and keep your car cooler.

 

[vetteoz]

So much for accuracy in a FSM...

Your car is obviously wrong; the FSM is the bible :ugh

 

[vetteoz]

You could wire it to the windshield wiper, when the key is turned on your fan will run all the time, and keep your car cooler.

So you have your wipers and fans running at the same time?

 

[nelson84]

So you have your wipers and fans running at the same time?

No, your wipers always have power to them when the key is turned on. Ever notice when the wipers are going and you forget to turn them off and you turn your key off and they stop right when you turn the key off. So if you wire it right to the fuse panel to the wipers it will run always when you turn the key on. But you can shut the wipers off, because there is a shut off on your door. But there is no shut off for the fan. Just a cheap and easy way to have a continual fan running once you start your car. Thats if you want it to run all the time. Or you can get the kit with the manual shut off and once in a while you will forget to turn it back on.

 

[gw962]

Your car is obviously wrong; the FSM is the bible :ugh

Darn, now I'll have to burn my car

 

[vetteoz]

So if you wire it right to the fuse panel to the wipers it will run always when you turn the key on.

That would only supply key on power , you still need a means to turn fans on because fan relay is grounded by the ECM.
The relays already have a power supply ; you need a switch to ground to turn them on.
Using your theory, you would use another relay closed by key on power; to ground the fan control wire when ign on.
In any case it is wrong; you don't need the fans running when road speed over 35mph and running them full time is only going to burnt the motors out

 

[nelson84]

It is an 85 and it still has the original motor for the fan. Even at highway speed it keeps it cooler than normal. To be honest the vette came like that, from the previous owner. I bet he had problems with it and wired it up like that. I wouldn't know where to start to put it back the way it should be.

 

[vetteoz]

It is an 85 and it still has the original motor for the fan. I wouldn't know where to start to put it back the way it should be.

The OP's car being discussed is a '90.

In your '85 case ,the ECM controls the fan BUT it has a temp switch in the head as a overide backup.
If that switch was faulty then it could run the fan full time.