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We have been testing several brands and types of fan controllers to try to replace those on the 1987-95 cars that are failing.
It seems that either the fan amplifier unit (under the hood, next to the hood latch) or the fan controller (mounted in the car next to the passenger seat on LHD cars) are burning out with no reasonable replacement available. I know Roger was having some of them rebuilt for a while, and I heard that he doesn't anymore. And I also understand that its getting harder to find a good used one, too.
We found a unit that can control any number of fans adding up to 65 AMPS, it fits where the original fan amplifier unit was mounted under the hood, and it uses the factory fan wiring. I've installed it, tested it, and written up a good set of instructions for the 928'er to install it with. This model uses PWM (Pulse Width Modulation) technology to start the fans at 60% and then increase fan speed as needed as temp rises; decreasing fan speed if the temp falls (like on the interstate) - providing excellent temperature control.
I believe I have the kit priced right - I am coming to market at just $198.15 for this, which is well below any OEM replacement. Again, it replaces BOTH the Fan Output Amplifier PN 928 618 421 00 and the Fan Controller PN 928 618 418 00 with one easy-to install and wire controller.
That Derale controller is a nice unit. It is a licensed implementation of the venerable DC Controls design, but with a nice case and modern manufacturing. I know several 928ers have used the DC Controls unit in the past with great success.
Good choice in controllers. I was thinking of modifying my fan shroud to include mounting of the drop-in version of this controller.
That Derale controller is a nice unit. It is a licensed implementation of the venerable DC Controls design, but with a nice case and modern manufacturing. I know several 928ers have used the DC Controls unit in the past with great success.
Good choice in controllers. I was thinking of modifying my fan shroud to include mounting of the drop-in version of this controller.
Glad to hear others have had good experience with this controller also.
My fans went into failure mode and I immediately thought it was either the controller next to the passenger seat or the "amp" under the hood. I did a lot of research and was about to buy the DC controls unit when Theo started helping me do some troubleshooting, ending with replacing my original amp with one he rebuilt. The fan problem persisted. The problem was simply overheating fuse contacts in the CE. I eventually had to buy a donor panel and replace the fuse block containing the two 30A fan fuses. It was a good time to give the Deox-it treatment to the entire panel and replace all the fuses. Still, this Derale product would be my choice when either controller or the amp fail. The really nice feature of the DC Controls design is continuously variable speed control, while still providing the default setting (both fans on full) when AC is on.
Last edited by Captain_Slow; 12-28-2018 at 12:44 PM.
That looks like a nice unit, Carl. I have used the Flex-a-lite controllers for a few years, and they have lasted 2-4 years each. When my current unit dies, I may try this one. My 84 has numerous electric fans due to supercharger setup.
Thanks,
Dave
That was my experience with other controllers too - you pretty much had to install one controller per fan and even then they didn't last. We really like the heft of this one, and a typical 928 will be running about 40 amps at startup through a controller designed for 65 amps, so I like the over-head. It makes me think that the controller is under-stressed and should last a long time.
For the 16v guys: we do also have a kit to remove the belt driven fan and it comes with a good (albeit smaller) electronic controller too.
Out of curiosity, which temp probe are you using? I saw the new one at PRI this year that they recently started sending with the units, looks pretty good.
It isn't a probe per se. It is a little black rectangle with adhesive on it. You can stick it anywhere on the radiator you like, but closest to the hot side hose bib is best. That's the right side of the radiator, top.
You can see the temp sensor attached to the top of my radiator in this picture.
Carl, can you expand some on the sensor location please? I did some modeling, looking at discharge temp as the factory did, and see that the top location you show results in some interesting temperature variation as speed and load change.
Carl, can you expand some on the sensor location please? I did some modeling, looking at discharge temp as the factory did, and see that the top location you show results in some interesting temperature variation as speed and load change.
+1
I would have expected it to be located close to the bottom hose to measure the temp of the water returning to the engine (the cold side).
According to Derale:
SENSOR LOCATION The controller is designed to monitor the coolant going back in to the engine, therefore controlling the engine temperature vs. reacting to it. By design, the sensor MUST be installed on the COLD SIDE of the radiator tank.
Controlling the return to the block offers better control and less fan interaction i.e. also utilizes the cooling air to regulate how the fan runs than the water coming from a hot block.
+1
I would have expected it to be located close to the bottom hose to measure the temp of the water returning to the engine (the cold side).
According to Derale:
SENSOR LOCATION The controller is designed to monitor the coolant going back in to the engine, therefore controlling the engine temperature vs. reacting to it. By design, the sensor MUST be installed on the COLD SIDE of the radiator tank.
Controlling the return to the block offers better control and less fan interaction i.e. also utilizes the cooling air to regulate how the fan runs than the water coming from a hot block.
That sounds like a great idea. I may move my sensor. How does one set the temperature point?
Thanks,
Dave
I just watched the Derale installation video and I now agree with you. Not sure where we got the idea that they recommended the sensor be installed on the inlet side, but we did. (is there an imogee for a face-palm?) I will change our instructions.
Good catch!
The sensor can attach to the radiators very easily on the end tank near the hose bib with the 3M bonding pad they supply.
Not sure where we got the idea that they recommended the sensor be installed on the inlet side, but we did. (is there an imogee for a face-palm?) I will change our instructions.
.
The only people who do not make mistakes are the ones that do nothing.
Porsche set their fan programme based on water temps exiting the radiator so it makes sense to replicate that. That being said the radiator takes out about 6 degrees C of heat and if you did fix the sensor to the inlet tank then adding 6 degrees C to the factory setpoints would ultimately give similar results. Interesting that the temperature that we see on the dash panel is the water temp leaving the engine and yet the driver gets no feedback regarding the temperature of the water returning to the engine.
12-27-2018, 02:25 PM
New Master Fan Controller for the 928
