Should both fans kick on when hot?

I went and picked up a customers 98 355 today. I had to jump it because battery was low but not dead. It ran fine with temps at 180 on highway to 190 at lights. when i I got it back to shop I was away from the for less than a minute to open garage door and temps went to 250....only the driver side fan was blowing. My guess is that the pass side fan should have come on also. Any suggestions?

 

Driver side fan is the radiator, passenger side fan is the oil cooler, if I recall correctly.

 

There is a oil cooler w/fan on the passenger side but there is also a radiator w/fan on BOTH sides.

 

Also, there is one temp sensor to turn on BOTH fans at once at 190 and off at 179. Check the fuse on the one not running but thats pretty hot pretty fast with one fan still running.

 

Both fans don't turn on at the same time on my car, the drivers side fan comes on first. With the a/c on, the drivers side fan cycles on and off and the passenger fan doesn't come on until around 190.

Op, check your fuses, you most likely have a blown one or a bad relay for the passenger fan. It's a known weak spot on these cars, Ferrari apparently specced a non sealed racing fan from spal instead of a proper sealed fan and when they get older and dirt in the motor, they draw too much current and start blowing the fuses. My car was modified to have the fans use their own power lead from the battery through a thermal cicuit breaker, I assume due to this problem, though the proper thing to do is buy the sealed fans from spal.

 

Water temp never got above 190 at lights. Oil temp at a steady 210.... No pass side fan at all kicking on while sitting and idling. where is the fuse box/relays located?

 

On my 99 it's located behind the passenger foot rest. Should be a 30amp fuse.
My temps started getting up to around 200+ at lights recently so I checked and sure enough the passenger side fan fuse was blown.

It would seem to me that if the fuse is blowing then the fan must be going bad?

 

Check your fuse, same thing happened to me.

 

See there now. I learn something new everyday! :>) I thought they both were for the core temp of the car....

 

Replace the fan on the passenger side soon. The fuse is blowing for a reason. So many owners keep replacing the fuse and never get to the root problem which is the fan drawing too much current and eventually will damage the fuse box.....think you have problems now?

 

I don't claim to be an expert here but this is my understanding. According to the owner's manual, the LH radiator/AC condensor fan comes on at 190 and goes off at 179. It is controlled by a coolant temperature sensor located in the top of the LH radiator. The RH radiator/engine oil cooler fan comes on at 194 and is controlled instead by the ECU which, in turn, gets its signal from a different coolant temperature sensor located at the cylinder head discharge at the rear of the engine.

I've only had my '96 F355 Spider for a few months now so haven't had a lot of experience with hotter summertime temperatures. However, the other day, it was 92 with moderately high humidity. Interestingly, fan behavior was no different than on other much cooler days. Typical stop and go city driving in traffic would cause the temperature gauge to almost reach 190 when the LH fan would come on. It would run for perhaps a minute or so, dropping the temperature back to about 180 and shut off. If I stayed in stop and go traffic, it would continue to recycle exactly the same way every so often (minutes).

To the best of my knowledge (and as would be expected from reading the manual), the RH fan never came on since the LH fan alone was sufficient to keep the coolant temperature below 190 (note that both radiators are connected together so any ram air flow from speed dependant motion is always cooling both simultaneously).

I'm only guessing here, but I'd expect things to be a bit different if the outdoor air temperature/humidity gets significantly higher (upper 90's/low 100's). That might (would?) exceed one fans ability to keep coolant temperatures below 190. If that were the case and 194 coolant temperatures were reached, I'd expect to hear the LH fan to already be running and have the RH fan come on then as well. The manual is silent about this but I'd expect both fans to shut off together as soon as the coolant temperature drops to 179, the same cycle then repeating if/as needed.

Another observation, if I avoid stop and go driving, even on a relatively warm day (92), and can get my speed up to around 45 MPH or so, even for a short while (minute or two), the coolant temperature always drops to 180 and stays there with no fans needed.

Hope this helps.

 

and this, sir, is exactly how the system works !

 

So, I have a question. If for some reason there is a failure with the ECU or anything that has to do with kicking on the fan and there is a major temp. spike. What steps should one take as to avoid major damage. I realize that shutting off the car is an obvious first step. Is it as simple as that until one can repair?

 

Well, getting the car up to highway speeds will cool it down faster. The fans on my car don't turn on at highway speeds at all, the airflow is sufficient to keep it cool. My right fan also rarely turns on, usually just the left fan.

 

Same here