still problem - electric

Check and clean all the ground connections.

 

I had a similar problem. The fan blades were free wheeling on the shaft. The motor would run, but the fan blades would not spin so it never felt like the fans ever ran. Replaced the fan.

 

It sounds like there may be a wire in the fan circuit that may be grounding out somewhere.

 

Each fan has it's own fuse #20 & #24 and relays #S & #T. Check those (swap the relays and see if anything changes).

 

Hang on & back to basics : aren't the 355 fans are separately controlled so they never come on at the same time - in which case that is why only one fires up at first

 

The RH fan is triggered by the ECU referencing the coolant temp sensor, which is located just to the right and slightly forward of the oil filter. So this fan would run 'full time' once the engine reaches operating temperature. This fan also draws air through the oil cooler located in front the RH radiator.

The LH fan is triggered 'mechanically' by the large thermal switch located on the upper 'end tank' of the LH radiator itself. This fan runs 'intermittent' as needed to maintain a steady coolant temperature (about 180°-190° F). This fan also draws air through the A/C condensor located in front of the LH radiator. So in addition to coolant temp the LH fan is also triggered by the needs of the A/C system.

 

He has a 348. Both cooling fans are triggered by one temp switch. The ground for the right fan and the temp switch are in the same spot and the ground for the left fan is in it's own spot which is probably why the left doesn't come on. The left ground is probably suspect. Check to make sure it's good. If you find it's problematic then I would check all the grounds I could find because that might definitely cause undo load on the system. You can check the service manual for these items if you like: 77 is the switch, 80 is the left fan and 82 is the right fan. Also you could have a mild short which might cause the problem.

 

On my '95 355, the right hand fan only runs when the oil temp is up around 210. Left hand fan runs intermittently when either coolant temp gets to around 190 or when the a/c is on. Maybe they changed things later on in the 355 run? The right hand fan does not come on very often for me as oil temp usually doesn't get that high.

 

Hmmm...you did say right. I don't know exactly where the ground is. You have to track it down. I'm just going by the schematic in the service manual and it says that ground is shared by the cooling temp switch, oil temp switch, Right hand fan and oil cooling fan. Check the positive on that side for a short also.

 

oops ........... I guess I though only the 355 has fan issues ...........

.......... I used to believe the oil temp sensor under the oil tank was what triggered the RH fan .......... but I recently did some research for a friend and I found out the oil temp sensor under the oil tank, is actually a temp sender for the oil temp 'gauge'.

The give away was that F1 355s did not have an oil temp gauge and also did not have that sender under the tank. So after I did more reading and actual testing on my 1997 ..... I found out the coolant temp sender next to the oil filter was the RH fan trigger and the ECU reference for A/F administration. There is a separate coolant temp sender for the coolant gauge ......... it is located about 6" forward of the coolant temp sender for the ECU. Seeing as how the oil and coolant get warm at about the same time the RH fan turns on, is what caused me to previously think the oil temp was the RH fan trigger ............

The test I did was to disconnect the coolant sensor (next to the oil filter) and the RH fan did not turn on, even after the coolant temp was at 190° (via gauge) and the LH fan began cycling. Where as before the RH fan would turn on before the LH fan.

 

The temp setting for the RH fan must be at a higher temp because I usually only hear the LH fan cycling on and off. The only time the RH fan comes on is when the oil temp is also high, which makes sense as that's probably when the engine is overall hot enough to trigger the fan. I haven't had any issues with the fans (that I can tell), both fans work, no fuses blown and I've never seen the coolant go over 200 or the oil go over 210 and it was 92 degrees out yesterday. A/C is also nice and cold, which seems to be the exception rather than the rule...

Hope the op figures out what is going on, sounds to me like a short in the wiring especially if it does it with the fan unplugged.

 

My Porsche had crazy electric problems once. I traced it back to a bad ground point for the battery and a very worn out ignition switch. After I loosened the screws on the ignition switch it slid right out!

 

That's the tricky part mate, if you need the wiring diagram and can't read it...............then it's time to take the car to an auto-electrician or learn how to read it yourself.

The wiring diagram tells you all you need to know to diagnose the problem.

I saw your other thread. If both fans spin freely, then there is probably no high resistance in the fan motors themselves, but there could be resistance in the plug or wiring associated with them.

**I haven't gone back to read your other thread or this one entirely**

Your call as to how you want to proceed from here. It's a great learning experience, but if you have no experience reading wiring diagrams then you are going to have to learn or hand the job over to someone else.

The Ferrari wiring diagrams are not too bad and I bet an experienced auto-elec can read it and probably fix it quite promptly. GOOD auto-elecs are worth their weight in gold.

 

How about with the engine off manually triggering the temp switch 77 by jumping it, then unplug the fan in question and measure the voltage available at the fan connector? You should see 12v there. If you see less or open, your fault is likely in the wiring. Measure the positive lead in the connector against a known good ground, I.e. battery.

Reading 12v now? Your ground is bad. Trace it back from the connector or run a dedicated lead (if you want a short cut or just temporarily see if that fixes the problem).

Not reading 12v against battery ground? If the fuse and relay are okay (presuming you checked by e.g. swapping against those from the working side) the problem is in the wire from the relay to the fan. I'd think that's less likely. The parts book does give you a general idea of how that harness is routed. Before getting into tracing that though, I'd run a direct temporary lead from the relay to the fan just to make sure it fixes the problem.

Let us know what happens.

Jay.