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Rad and Eng Fan switch DIY?

MJH1
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hasteyrb Member

hasteyrb

Posted
Posted

Hello Guys

Is there a good DIY on how to install manual switches for the rad fans and the engine compartment fan on a 99 C2 cab?

Thanks for the help.

Here is something I came across below:

"Radiator Fans

Connect a wire to the ground of the 2 high speed fan relays located on the relay carrier located in the driver’s side foot well. The relays are #20 and #22. Feed this wire to where your switch will be located. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and then connect the other end of this wire to a chassis ground point.

(Just remove one of the fan relays, insert a 16/18 gauge wire in the #85 socket and put the relay back in. Now, touching the other end of the wire to any ground on the car (bolt,frame, etc) will start the fan. Removing it from ground with stop the fan. Now all you do, is get a switch and connect the wire from the replay to one side and another wire from a ground to the other side of the switch. You now have a way of turning the fans on and off. All you have to do is decide where to put the switch.)

With key on, this switch will now immediately turn on both radiator fans providing maximum cooling. When you turn the key off, the fans will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off.

Engine Compartment Fan

Connect a wire to the ground of the relay located in the relay carrier behind the passenger seat, driver’s side. Relay #8. . Feed this wire to where your switch will be located. I simply fed the wire along the driver’s side of the car and under the door sill. Connect the wire to one side of the switch. Connect another wire from the other contact on the switch and connect the other end of this wire to a chassis ground point.

With key on, this switch will now immediately turn on the fan drawing air into the engine compartment. When you turn the key off, the fan will continue to run for about 5 seconds until the relay shuts down. Your fan operation remains normal when the switch is off. This mod helps keep the engine compartment much cooler when driving around town and is particularly beneficial to any engine that draws its intake air from inside the engine compartment, such as the EVO SC.

If you are adventurous, you can automate the operation of these switches so they will switch off at a specific speed, or operate when vacuum is present only, etc. You can choose any style switch you want and even use Porsche switches (relay may be required). I simply used 2 toggle switches that I installed in the batwing."

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Loren Member

Loren

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IMHO - if your car is cooling properly you do not need these fan switches.

).I live in an area of California that hits up 115 F (about 46.1 C) during the summer and the stock cooling system plus the 3rd radiator handles that just fine (including laps at Laguna Seca).

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MJH1 Member

MJH1

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My car does seem to cool as it should, from what I can tell from posts here and other sites my temp needle is at the 0 (in 180F) or just a hair to the right of 0 (which seems to be the norm?) just figured that on some really hot days these fans being turned on might help keep temps down a little, with out having to go to the expense and time of installing a 3rd rad, also not sure if installing the 3rd rad is with in my DIY skill set.

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Loren Member

Loren

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My car does seem to cool as it should, from what I can tell from posts here and other sites my temp needle is at the 0 (in 180F) or just a hair to the right of 0 (which seems to be the norm?) just figured that on some really hot days these fans being turned on might help keep temps down a little, with out having to go to the expense and time of installing a 3rd rad, also not sure if installing the 3rd rad is with in my DIY skill set.

Most folks don't need the 3rd radiator either. I got mine because of my locations high temperatures and track time use. The 3rd radiator really helps when the car is moving but does little when stopped.

It sounds like your is normal so I would just keep the radiators clean and the car's DME will turn the fans on when needed.

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MJH1 Member

MJH1

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I ended up not doing this mod, found out my coolant tank had a crack in it. I replaced it and now the car seems to be running cooler, it must not have been building the pressure needed with the crack. New tank in and all seems to be good

Thanks for the input.

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Doohan Member

Doohan

Posted
Posted

Just changed the left resistor, everything is working now! ;)

Hi Loren, when you turn the AC on does both the front fan should turn on?

I'm trying to see if I have a fault on my left fan resistor...

Yes, when the AC is on both front fans should go to stage 2 - high speed.

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Loren Member

Loren

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Just changed the left resistor, everything is working now! ;)

Hi Loren, when you turn the AC on does both the front fan should turn on?

I'm trying to see if I have a fault on my left fan resistor...

Yes, when the AC is on both front fans should go to stage 2 - high speed.

:thumbup:

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