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C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Manual Fan Switch Installation

 
Old 01-22-2008, 08:54 PM
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IceDazzlr
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Default Manual Fan Switch Installation

Has anybody installed a manual fan switch in their 1994 Vette? If so could you give me some details how you did it. I bought the switch from MAMOTORKS (Mid America) and the illiustration of the fan relays and just how the wires are to connect to them are not very detailed.


Last edited by IceDazzlr; 01-22-2008 at 10:31 PM.
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Old 01-22-2008, 10:12 PM
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jfb
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I installed my own switch on my 87, it should be the same as a 94. Connect a wire from the fan relay ground wire (green/wh on an 87) and from the engine compartment snake it through the rubber boot in the door and into the passenger compartment. Connect the wire to one switch teminal and ground the other switch terminal. With the ignition on, when you turn on the switch, the fan will run.
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Old 01-22-2008, 10:21 PM
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Johns87
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Hello,
I did a similiar change. I wired My front fan on My 87 to a relay and hooked itup so the front fan came on with the ignition. If you will look at the wiring schematics of a standard relay (like used to wire aux. lights), You will see that they can be wired to activate from ground or hot connection.
I hope this info helps, Sorry I don't have the schematic in front of Me right now.
Take Care, -John
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Old 01-23-2008, 05:07 PM
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Most of these switch are temp switches (button head are switches, the spade connector are sensors) that are installed on the head of the driver side (between 1 and 3). The wire then gets routed to and tapped into the Fan Relay ground wire (Green/White)... You can also add a wire to a manual switch (in/under the dash) that will manually ground the relay and turn on the fan.

You can either just use the temp switch or manual switch to activate the relay or both.

It is really that simple.
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Old 01-24-2008, 11:59 AM
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Why would you put a manual fan switch in. If you are having cooling problems get rid of the the stock gm fan and put a 88-93 Ford Taurus 2 speed fan in it and be done with it. with a manual fan switch in it you will just burn up the fan motor faster and you will not gain better cooling you will still have the same problem. Now if your trying to cool it down between runs at the drags or like the sound of your fans running all the time weeeelll then nevermind
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Old 01-24-2008, 11:23 PM
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Thanks for the help. Installed my manual fans swith tonight and it's fantastic. Both fans come on when I want and it does help cool the car when the temp gets above 215 degrees. I love it!
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Old 01-26-2008, 11:32 AM
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I was reading up on Mid-America's kit and there instructions.. They use a three position switch, Off, manual and switched.

If you are also using a Temp switch in the head you can also set this up, as it is a simple to do.
Put the new switch in the Head, run the wire to one pole of the switch, ground the other pole and then for the middle pole run it back to the relay (green/white)..

that way when it is off/center, the ECM is controlling the relay, when it is on Temp switch side, it will come on at the temp that the switch is setup for (160, 170, 195, etc), and 3rd, is the manual override.

Maybe a rocker switch like the one that is used for the Mirror side select would work. And install it on the console or the dash and it would like factory...?
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Old 04-14-2008, 08:31 PM
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Surfin' Elvis
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Seems to me Mid-America's kit for the 94 cooling fan switch is only on/off.
My fans aren't coming on at all and I just replaced the secondary fan motor because I thought it was bad. New fan relays, too.
I'm gonna install a switch (don't see the need for a 17 dollar kit, however) and try it out this weekend. Hope I can make something happen soon. This car's gonna kill me. I'd rather just have the 67.
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Old 04-15-2008, 12:55 PM
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Originally Posted by jfb View Post
I installed my own switch on my 87, it should be the same as a 94. Connect a wire from the fan relay ground wire (green/wh on an 87) and from the engine compartment snake it through the rubber boot in the door and into the passenger compartment. Connect the wire to one switch teminal and ground the other switch terminal. With the ignition on, when you turn on the switch, the fan will run.
I did it this way also about 4 years ago or so on my 94. I obviously connected to the secondary fans relay and used the dark blue wire #473 to close the relay. I never thought of getting a fan kit. I just used the parts that I usually have at home.

FYI – When the switch closed and the relay is energized, the PCM sees this as a fault since its not expecting to see a short at that point at that time since it did not tell it to close the relay. So it will throw a code (can’t remember I think 78?) that will always be stored in the PCM. Will not affect anything and no indication (SES) that it is stored.


Originally Posted by vetteset8087 View Post
Why would you put a manual fan switch in. If you are having cooling problems get rid of the the stock gm fan and put a 88-93 Ford Taurus 2 speed fan in it and be done with it. with a manual fan switch in it you will just burn up the fan motor faster and you will not gain better cooling you will still have the same problem. Now if your trying to cool it down between runs at the drags or like the sound of your fans running all the time weeeelll then nevermind
Respectfully disagree with much of this. My cooling system works exactly right as it was designed with no abnormal problems. Here in Orlando where its hot most of the time, and hotter in the summer, the primary cooling fan just does not pull enough air in to keep things cool when standing in traffic. My A/C runs 99% of the time, even in the winter to keep the moisture off the inside of the windshield.

The duty cycle of the secondary fan is much less than the primary which runs all the time when the A/C is on. I only turn on the secondary fan when I get over about 210* or if it looks like I will be stuck for a while in traffic. The usage of the secondary fan is quite low and is probably no more than if it came on itself, but I am just doing it at a lower temperature. Secondary fans are not burning up.

Once I get rolling I can shut all fans off and come down to 195*. With only one fan running its doing the best it can in Orlando, which is not good enough when hot in traffic. With the second fan running the cooling is extraordinary better. There is no problem, things are working as designed.

As designed – opinion. The radiators are under designed for the car. I changed mine from a stock 7/8’“ GM to a new stock 1 ľ” GM. Made a nice difference. Larger radiators will help even more

Charge on

Last edited by pcolt94; 04-16-2008 at 06:37 AM.
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Old 04-15-2008, 05:25 PM
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polo91cnvt
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When you start needing the fan switch to cool it down, start saving for a new radiator and water pump. I put the new dewitt's and high flow pump on the 91 L98, along with a new t'stat and the car keeps the temperature of the t'stat.

Also check the ground sucking air intake for the radiator and clean it out, you may want to take and get in between the raidator and the a/c to get all the dirt out. This alone may solve your problems.

good luck polo
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Old 04-15-2008, 05:27 PM
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obrian
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Default switch change

I love reading about all the different ways we deal with things. I want my fan to come on at 200 and go off at 185. I ordered a switch from some on line place. I have installed a 180 degree thermostat. It cruizes so nice at 178 degrees and gets up to 230 in traffic. How can it be any easier than that. Why do we need all these wires and manual switches?
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Old 04-15-2008, 07:19 PM
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FOURSPEEDVETTE
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Default Factory settings seem OK to me

Mine in my 85 comes on at exactly 228 degrees and shuts down at I think 190. If the air conditioner is on, the aux. fan will also come on. It was designed to run like this from the factory and seems to run beautifully at these temps. It will shut the engine down at about 240 from what I am told so as not cause damage. Mine has never risen above 228 so I can't verify that but it is the manual.
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Old 04-15-2008, 07:38 PM
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No luck.
Tried grounding by splicing in to the blue 18 ga. wire to the primary relay and the green 18 ga. wire at the secondary relay and I still can't get either fan to come on.
New seconday fan motor.
2 new fan relays.
Good 30 amp primary fan fuse.
Good 40 amp secondary fan fuse.
What next?
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Old 04-15-2008, 08:40 PM
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pcolt94
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Originally Posted by Surfin' Elvis View Post
No luck.
Tried grounding by splicing in to the blue 18 ga. wire to the primary relay and the green 18 ga. wire at the secondary relay and I still can't get either fan to come on.
New seconday fan motor.
2 new fan relays.
Good 30 amp primary fan fuse.
Good 40 amp secondary fan fuse.
What next?
Not sure what your doing but the goal is to turn on the socondary fan, not the priminary fan. If you have the 94, itís the dark blue/red wire on the secondary relay. The wire gets connected to ground to close the relay. Read first part post 9.

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Old 04-16-2008, 07:55 PM
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OK, I am lost.
Tried the grounding of the blue wire at the secondary fan. Fan no work.
Tried grounding the green wire at the primary. Fan no work.
I have 12V input at both relays.
A/C on - no fans.
Defrost on - no fans.
Coolant temp up to 240, no fans.
I know both fans will work when current gets to them.
Is there any other way I can wire the fans to come on without seriously confusing my computer? I am thinking about running a hot and ground to each fan and hooking them to switches in the cockpit, leave the relays as they are but dead-head the output wires that run to the fans.
Y'all are gonna get sick of my questions, but this is getting to me.
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Old 04-16-2008, 09:34 PM
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No problem. (Make sure all fan fuses are good fuse #29 (5A), #2 & #5)

First, make sure you are on a real ground. Check it by going to the engine for continuity.

Next, Turn key to on (do not start) . Just to make sure the relay is getting voltage, measure the voltage on the blue wire, to ground (wire not grounded).

If voltage is there, ground the wire. You should be able to hear the relay click. The fan should start.

Follow this and re-post with results.
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Old 04-16-2008, 10:19 PM
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Originally Posted by jfb View Post
I installed my own switch on my 87, it should be the same as a 94. Connect a wire from the fan relay ground wire (green/wh on an 87) and from the engine compartment snake it through the rubber boot in the door and into the passenger compartment. Connect the wire to one switch teminal and ground the other switch terminal. With the ignition on, when you turn on the switch, the fan will run.
This is both the simplest and the safest. Mirrors what the car does, supplies ground to a relay.
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Old 04-18-2008, 07:25 AM
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I am almost embarassed to admit it, but the problem was fuse #29, a stupid little 5 amp fuse. I have been known to look for the most difficult problems first, but this one takes the cake!
Thanks pcolt.
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Old 04-18-2008, 09:20 AM
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This where I put my switches for the primary and secondary fans. In the off position, the system is normal. When the switch is on, it grounds the signal wire to the relays bypassing the ECM. Remember, above 35 mph the VSS turns the fans off, SO I have to remember to turn the manual switches off or they will run above 35 mph and that is not good, you'll get a "check engine light"

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Old 04-18-2008, 01:50 PM
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Originally Posted by Strick View Post
This where I put my switches for the primary and secondary fans. In the off position, the system is normal. When the switch is on, it grounds the signal wire to the relays bypassing the ECM. Remember, above 35 mph the VSS turns the fans off, SO I have to remember to turn the manual switches off or they will run above 35 mph and that is not good, you'll get a "check engine light"

This looks sweet. I hooked both of my fans into one switch. I put two mini switches on each side of the front cup holder under the lighter. One is for the fans and the other for the antenna.
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