High speed fan relay hack/mod

[greerj1]

Has anyone tried to short out the relays with a switch to run the radiator fans at high speed. Searched fan relay mod/hack and found nothing.

Thanks for your help.

James

[Loren]

Why?

If your car is overheating it is not because the fans are running too slow.

Did you know Cup Cars have no fans?

[ninsei]

Why?

If your car is overheating it is not because the fans are running too slow.

Did you know Cup Cars have no fans?

I'm interested in doing this too. I see this:

http://www.ppbb.com/boards/ppbbphp/showfla...;Number=1509504

But it's for a boxster (will it work with a 996) and I don't fully understand it. you run a shunt wire in the relay panel then reinstall the same relays?

[Loren]

Why?

If your car is overheating it is not because the fans are running too slow.

Did you know Cup Cars have no fans?

I'm interested in doing this too. I see this:

http://www.ppbb.com/boards/ppbbphp/showfla...;Number=1509504

But it's for a boxster (will it work with a 996) and I don't fully understand it. you run a shunt wire in the relay panel then reinstall the same relays?

If your car is overheating it is not because the fans are running too slow.

[1999Porsche911]

Radiator Fan and Engine Compartment Fan Switch Mod

The 3.4 996 runs extremely hot when driving around town in temperatures higher than 75 degrees. This mod is a way to reduce coolant temps back to a safer level, helping to reduce oil temps and improving performance.

The mod consists of installing a switch that will allow you to turn on the high speed radiator fans at any time, while maintaining the automatic operation of the fans. We do the same for the engine compartment fan.

Radiator Fans

Connect a wire to the ground (Pin #85) 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.

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. I simply used 2 toggle switches that I installed in the batwing,

Jim

[ninsei]

Thx. That's good info. I'm loking for something automated. how bout that link I showed about making low speed radiator fan speed equal high speed.

[ninsei]

I think I see. So what if my goal is to have the engine compartment fan turn on automatically, a little earlier (at a slightly cooler temp) than it normally would? Would connecting pin 85 of the engine compartment fan relay (relay # 8), to pin 85 of one of the radiator fan relays (say left, high, relay #20) achieve this (I know it's a long wire run)? Would it hurt anything? how do these relays work, regarding pin 85? I see from the wiring diagram that that goes to the DME (on both the rad fan and engine comp fan relays). Is pin 85 normally no grounded, then when the DME decides it wants to, it connects pin 85 (of whatever relay) to ground, then that sends +12V to pin 87 on said relay?

[ninsei]

or maybe I could connect pin 87 from one of the high speed fan relays to pin 87 of the engine compartment fan relay.

[jam996]

1999Porsche911, what switch did you use, anyway to make a illuminted one work?

I don't think you can use oem switches, you will have to keep your finger on it, you would need a relay to make it hold.

And for the radiator relays, Its one wire on each relay(ground pins), linkin together then going toward switch, right?

or different switches for both?

thanks

Edited September 5, 2009 by jam996

[1999Porsche911]

1999Porsche911, what switch did you use, anyway to make a illuminted one work?

I don't think you can use oem switches, you will have to keep your finger on it, you would need a relay to make it hold.

And for the radiator relays, Its one wire on each relay(ground pins), linkin together then going toward switch, right?

or different switches for both?

thanks

If you use the Porche swtiches you will need to install a self locking relay inline that will toggle on off each time you press the switch. I simply installed a 2 toggle switches in the batwing on the console, 1 for both radiator fans and 1 for engine compartment fan.

You are correct to tie the 2 ground wires from the fan relays together and connect at 1 switch.

Edited September 5, 2009 by 1999Porsche911

[jam996]

Great thanks,

I'll give it a try this week, and post some feedbacks.

[ericinboca]

or maybe I could connect pin 87 from one of the high speed fan relays to pin 87 of the engine compartment fan relay.

Are the grounds on radiator fan relay and engine compartment fan relay pin 87 or pin 85?

[Stefan]

That is my DIY for the radiator fan on PPBB (new link - http://www.ppbb.com/phorum/read.php?6,1509...04#msg-1509504).

With this hack, the fan will go on automatically; no need to fuss with a switch. The procedure is identical for the 996. You remove the relay, put in a jumper wire, reinstall the relay.

Edited October 2, 2009 by Stefan

[wwest]

Radiator Fan and Engine Compartment Fan Switch Mod

The 3.4 996 runs extremely hot when driving around town in temperatures higher than 75 degrees. This mod is a way to reduce coolant temps back to a safer level, helping to reduce oil temps and improving performance.

Or....(***)

You can turn the A/C temperature down to "freezing" and then manually adjust the blower speed to attain the desired cabin comfort level. The reheat/remix blend door will be fully closed to reheat, the compressor will run a LOT less often AND the heat load on th engine coolant radiators will be substantially reduced.

If the lowest blower is too cool then I switch the system to combined, floor and dash A/C airflow.

You can also improve the A/C efficiency more simply by installing a manual shut-off valve in the coolant hose to the heater core. Not even any radiant heating of the system airflow nor your right foot/leg, that way.

Improve FE to boot.

NEVER allow the system to automatically switch to windshield air outflow when using this technique. In point of fact it is wise to ALWAYS cycle the windshield airflow ducts open then OFF regardless to avoid inadvertent instances of outside windshield fogging, sometimes at the WORSE possible moment.

The mod consists of installing a switch that will allow you to turn on the high speed radiator fans at any time, while maintaining the automatic operation of the fans. We do the same for the engine compartment fan.

Radiator Fans

Connect a wire to the ground (Pin #85) 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.

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. I simply used 2 toggle switches that I installed in the batwing,

Jim

*** made this "discovery" back in about '00 in our '99 911/996. Hot, HOT day traveling across AR in stop and go construction zone traffic and the engine began to overheat because one of the front cooling fans had failed. Gave up on using A/C for a few miles until I came to the realization....

Necessity truly is the MOTHER of invention.

Edited October 3, 2009 by wwest

[ivangene]

That is my DIY for the radiator fan on PPBB (new link - http://www.ppbb.com/phorum/read.php?6,1509...04#msg-1509504).

With this hack, the fan will go on automatically; no need to fuss with a switch. The procedure is identical for the 996. You remove the relay, put in a jumper wire, reinstall the relay.

DUDE!

That worked perfect... now I KNOW its the resistor AND I dint need to pull the wheel well cover out.

My car thanks you!!

Ed