Radiator Fan Switch

According to the Ferrari wiring diagrams, OEM fan wiring is 6mm^2 (so at least 9 or 8 gauge on the American scale).

 

Go ask on the original thread linked in previous posts.

 

The oem + wire from the relay board to small fan is just over 2mm with insulation. My wires are over 5mm. I measured the small fan as I am no longer using that wire. I assume the oem large fan wire is the same size.

In the bottom photo the lower dark red wire runs from my alternator post, then is teed at middle radiator to the fuse holders, which then run to my 40amp relay wires, then to the fan leads. I also made a local ground strap with loop connector for the fan leads that attaches to the front structure.

Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login

 

Here is an incomplete pic of my set up.

At the top the fuse holders are teed into my fat alternator post wire. It was already attached so did not make the pic. The small fan relay is missing from the holder.

At the bottom is the ground strap with loop (I had red wire lying around).

The middle white and black wires are signal from the large fan relay board. I do not use the small fan wire signal. Both fans are triggered from the large fan signal with a 10 second delay for the small fan.
https://www.ferrarichat.com/forum/threads/456-small-fan-switch.599436/


Image Unavailable, Please Login

 

For clarification, my “6mm^2” refers to the multi strand copper conductor cross-sectional area, not the diameter of the plastic wire insulation.

 

Understood. Just trying to show relative sizes oem vs what I installed.

 

Not sure about post shut-off but the system should auto bleed air into the tank. You may want to check the small hose under plenum is not clogged or other problems allowing air to accumulate.

 

Sounds like the same symptoms I had. Coolant temp no problem as long as the the car is moving (and not necessarily highway speed, just moving), but closer to 200F when stopped with both fans working and if really hot outside, closer to 230F stopped in traffic. I installed new fans and wired them directly from the battery using the original wiring to signal on/off and that fixed the problem. I suspect some power is lost through the circuit board and the fan motors may also become less effective as they age. Since I did the new fans and wiring at the same time, I don't know which had the greater effect. I also put on a 575 fan shroud, but I don't think that was really necessary.

 

From my experience bypassing the fuse board has a greater effect than replacing the fans!

 

I had same symptoms - did the same fix with very good results. BTW I read your original post from a few years ago which prompted me to copy what you did - thank you. Regarding what is going on with these fans, I do recall that with my old fans I measured 16-17 amps going to each fan - that's a steady state number eg., not start up. Since they were both about the same the normal conclusion is that they are ok (or both bad in the same way). I replaced them anyway since I was working in that area - with the same part number fans - which have a lot larger motor now (they are not really expensive). That plus pulling power from the battery through some relays resulted in the fans blowing a ton more (eg before I actually had to put a piece of paper in the fan to tell if it was running - with this new set up they really blow and it is easy to tell they are running)..I've heard that when new the engine cooling in these cars worked fine so it looks like something is degrading over time. Another thing I did was pull the radiator and had it cleaned out (by a radiator shop) - that had marginal benefit but is another thing which normally gets less efficient over time.

Regarding the shroud: the 550 shroud covers about 2/3rds of the radiator and the 575 covers 100%. I think you are correct that changing to the 575 shroud may not be necessary (in addition to changing the fans and redoing the wiring). My thought is that the 575 design is the better of the two for in town driving - with lots of stops and low speed driving. It may not be optimal for high speed driving (eg racing) however. There I think the 550 shroud is better.

 

I'm not sure if there are any plug and play solutions for the 550. I could only find 10 amp timer (5 pin) relays for sale, not enough for typical fan currents. You may have to chop up good wiring to insert a time delay relay in the fan relay (coil) wiring... or... if you intend to add one of those previously mentioned relay kits, then perhaps plugging one of these timers into your normal relay slots would work?

https://www.ebay.com.au/itm/322122616177

Video for timer setup here:



Image Unavailable, Please Login

The pin configuration seems to mostly match the standard 550 relay, but I'm not sure why there is an output on pin 87a on the timer relay. Is it required to keep the fan running with power off?

30 = live battery power
87 = output to fan
87a = not used on 550
31 (or 85) = earth
15 (or 86) = power from HVAC for turning on the relay.

 

Instead of timer running after shutdown another option is to use temp sensor. If temp is above threshold keep fans running when engine is turned off. Some Porsche's have use intake temp sensor for this.

 

Yes, the pin configuration on that timer relay looks tempting, but it can't be substituted because of the way pin 15 works (and only being 10A). This is a better description of how it works:

https://www.12voltplanet.co.uk/adjustable-delay-timer-relay-delay-on-or-off-12v-10a.html

It could be made to work to keep running the fan after engine shutoff, but you would need something to put a momentary +12V signal on pin 15 at engine shutoff (so DELAY OFF mode operation), and then this timer relay would output a +12V signal on pin 87 for fixed time = then you would need something to take this +12V signal and turn it into a ground signal to close the fan relay (or have another relay to run the fan which has the logic of +12V closes it rather than a ground signal closing it like the stock fan relay).
Seems like a lot of added "somethings" .

 

Is is added or is it already present, Steve? How is a "momentary" signal defined? The HVAC ECU is sending voltage to pin 15 when the fans are commanded on. When the ignition is turned off, the voltage on 15 disappears. You could say this is momentary (not permanent).

Delay before OFF mode
When a voltage is applied to terminal 15 (the timer trigger) the relay will switch power to the output (terminal 87). As soon as the voltage is
removed from terminal 15 the timer will start and power will continue to be fed to terminal 87 for a user-settable period of time before the
relay switches off. The relay will remain in this state until a voltage is once again applied to and removed from terminal 15

This timer relay is effectively a changeover relay, so power from 30 is routed to either 87 (NO) or 87a (NC) depending on whether the relay is
active or inactive

Delay before OFF mode
When a voltage is applied to terminal 15 (the timer trigger) [from the HVAC] the relay will switch power to the output (terminal 87). As soon as the voltage is
removed from terminal 15 the timer will start and power will continue to be fed to terminal 87 for a user-settable period of time before the
relay switches off. The relay will remain in this state until a voltage is once again applied to and removed from terminal 15.

Terminal 15 is the timer trigger and requires either a momentary or permanent +12V/24V supply depending on the selected mode.

As I see it, the 10 amps is the only thing missing, but it can be used as a trigger for an auxiliary power relay closer to the fan/s.

If it wasn't so expensive, I'd buy one and try it on a lower power circuit to see if it works.

 

It's not really clear to me either, but this document:

https://www.12voltplanet.co.uk/user/downloads/User%20Guide%20For%20Adjustable%20Delay%20Timer%20Relay%20%2012V%20&%2024V%2010A.pdf

seems to indicate to me that there are two different relay configurations available from the manufacturer (not that a single relay can operate in either mode) -- see the last FAQ.

 

I guess you only need one mode in this situation.... delay OFF... although it would be good if you could stagger the two fan startup times by a few seconds to reduce the load on the electrical system.

Even if I had the relay, I can't think of anywhere to test it. The horn relay position? I think that would annoy the hell out of my neighbours, depending on the time duration

 

Aerosurfer's relay kit arrived in the UK this week. I was really impressed with how well made everything is.

I thought that I could create something myself, but there is no way that I would have been able to get anywhere near this professional standard.

Highly recommend this kit!

 

Appreciate the kind words. Have fun with the install. Reach out if you have any questions

 

My car doesn’t overheat since I had the radiator recored a few years ago.
The problem that I hope to solve is avoiding the potential damage to the original fuse box from the electrical load of the radiator fans. This is a well known 456/550 improvement.

 

A faulty TGK Valve might cause this

Image Unavailable, Please Login

Image Unavailable, Please Login

The TGK /hot water Valve is controlled by the HVAC ECU. At the moment, I'm having trouble tracking down a wiring diagram for this system. On the F355, the driver chips in the HVAC ECU are known to be a problem. I'm not sure about the 550.

The TGK/hot water valve is actually in the cabin near the driver's right leg.

Image Unavailable, Please Login

 

The TGK Valve on the 550 is the same as the TGK valve on the Ferrari 360

Internally, it looks something like this:

Image Unavailable, Please Login
(although I'm not 100% sure of internal wiring).

There will be two wires for the motor. The HVAC ECU changes the polarity of the voltage on the motor to open and close the valve. The other 3 wires are for position feedback. It's difficult to do wiring checks on these valves because as soon as you disconnect the plug, the HVAC ECU stops sending motor commands to the valve.

You could disconnect the plug and try putting a voltage on the red and black wires to see if the valve runs open/closed. Sometimes these motorised devices will run on a small 9V torch battery.

Image Unavailable, Please Login