firemn131

Fuel test tonight went well...No leaks

Wanting to test the fans before install..
I put 12v to them and they just hum and want to turn. Effort and sound is identical to both fans

Is this normal?
What would it take to get them to run out of car?

Thanks

potdog

Hi there they should run with power supply . I have listed new Bosch fans on Rennlist before and sold two set's to Rennlister's

dr bob

What 12V source are you using to test the fans? They take a lot of current. Fused at 25 Amps each, they have a habit of drawing enough current to melt the fuseholders. So if you are using a small battery charger for instance, you may need to find a bigger power source if you want them to sing instead of just humming.

firemn131

Thanks Bob,,
I was using a battery tender..lol

yea I needed more juice.

Charley B

That's exactly what happened to mine. I want to run a separate circuit to a switch in the cockpit. Do I need to run separate circuits with each fused at 25 amps or can I run one switch circuit with one fuse. Or do I need to do an inline relay? I'm pretty ignorant about electrics so I don't mind a lecture about this idea.

FredR

Charley,

I thought yourmodel year had mechanically driven fans? Has it been hacked- what exactly do you have in there?

In simple terms the later models have two chunky fans driven by two separate circuits and a control system that enables fans to be run when needed and both driving from the moment the a/c is switched on [as I understand]. If you have a track car and need non of the sophistication then mounting an electronically controlled system is not too difficult, especially if you want to manually control things.

Having no idea what you have to start with, let's assume nothing and take it from there.

First of all for fans there are several options in your case- you could try one large 16 inch fan or go down a route similar to Porsche and have two 12 inch fans. Spal do a neat twin fan kit that used to go for $275 from the "fanman.com". This is a neat piece of kit I have been using for 10 years without any issues but it has a quirk in that one fan motor is fully weather proof and the other is not for some bizarre reason so how this works out in heavy rain I have no idea. The design is very compact but it needs some working to get it to fit- I made some brackets out of one of my wife's aluminium kebab skewers [she went bonkers!].

In my case I use the stock GTS electronics/control system and it works fine providing you get the polarity correct!

In your case you would need to run a power supply from the hot post. The first leg of this is an in line fuse with a decent size fuse [like the 25 amps] or less depending on what is connected. You then need a relay kit- SPAL do one for about $40, JEGS do one for even less. Obviously you need two of these for a dual fan set up. These kits contain a fully sealed weatherproof relay and a pretty decent amount of cabling to custom fit to needs.

If you are only interested in a cockpit on/off select switch the wiring on the relay itself will probably be enough to get you into the cockpit. You would need to run 12 volts to the cockpit switch[with a small in line fuse-5 amps?] and on the other side of the switch connect the input to the relay. The Spal kit actually marks the cables to indicated what they are, the bigger ones being power in/out.

The Spal fan kit has weather proof connectors for shroud removal and pig tails to wire back to the power supply so you will not be short of cable. indeed there is probably enough to wire back to the battery box if you wanted!

If you want to be a bit more sophisticated you can also run a temperature switch to turn the fans and/off at a specific set point temperature connected in the relay circuit and SPAL even do a programmable controller wherein you set the temperature you want it to switch on. Doubtless there are many after market such devices.

That is about it really

John,

Regarding your original query, you should be able to run the fans one at a time from a battery- just be careful not to short the leads or you will have an arc welder on your hands. Again an in line fuse is better when trying such. If your fan motors are the original ones they are probably pretty fired by now- another member of the "sooner or later" list.

Rgds

Fred

Charley B

Thanks for the great input Fred. I should have added more info., I have a Euro 4.7 CIS with an S4 fan set. It keeps over loading and burning the fuse holder. I was a couple hundred miles from home so I ran a hot lead off the jump post with a spade connector as a temporary "get me home" fix. I thought of moving it to a different fuse location on the board but I'm leary of creating too much heat down there.

FredR

Charley,

The question now is what elements do you have to control your fans at the moment?

If it is a half assed DIY special then it might explain the over heating problem as those stock fans are pretty chunky items. Also, if they are failing in say the bearings maybe they are drawing more current than they should be.

Rgds

Fred

Charley B

Thanks Fred. I'll do a draw test and see how many amps they are pulling.

firemn131

Well, My fans work.
Not sure if they are 100%, but they were cycling through when I drove it tonight.
Another milestone!!

firemn131

Well, My fans work.
Not sure if they are 100%, but they were cycling through when I drove it tonight.
Another milestone!!

FredR

John,

Some things on your previously suffering car must work correctly- not everything is TBF'd!

Long may she bounce around in the crankcase!

Fred