Shark Attack

When is this fan to operate? I don't think mine is kicking on. 99/ 996 5 speed.

Thanks
Kyle

trendy996

When the engine bay temp sees a certain temp. The sensor is located on the passenger side intake manifold. They typically never do unless you live in a hot climate. I removed mine and live in Ohio. I believe the gt3 doesn't even have one.

Macster

Good grief. Even in the mild climate here in northern CA the thing comes on in my lowly 02 Boxster.

It comes on more often in my 03 Turbo.

IIRC the trigger temp is 135F.

Anyhow, with it removed I hope you enjoy cooking your car's engine compartment and all hardware -- especially that expensive harness -- that resides in it.

Ubermensch

Interesting to hear your experience, Macster. Mine is the exact opposite and when i search previously I saw similar answers. My fan rarely turns on in my 2001. Even at the track...so I start checking fuses, relays, etc. Everything is in good working order. I eventually pulled the temperature sensor and let it dangle near the headers. That kicked the fan on immediately. I'm not sure what temperature it's set for (I thought 180F), but it operates quite rarely for me.

Shawn

7500rpm

My 997 fan kicks in strangely at times. It could be a hot day and its not spinning while it would sometimes kick in at a seemingly cool day. Do a search, I recall reading somewhere several parameters control when the fan is activated, which includes when the engine is not even running.

Kazual99

Living in CLT my fan never comes on.

Loren

It is rare for the engine purge fan to come on at all.
Mine only comes on after I come off the track while I am idling during cool down.

"Switch-on conditions for engine compartment fan (this fan pulls air into the engine compartment) The engine compartment fan is switched on when the engine compartment temperature is > 176 degrees F or the coolant temperature is > 216 degrees F.

After-running of engine compartment fan
If the ignition is switched off and the engine compartment temperature is more than 140 degrees F, the DME control module remains in readiness for another 20 minutes. During this time, the engine compartment temperature is retrieved every 10 seconds. If the engine compartment temperature is > 185 degrees F , the engine compartment fan is switched on for 20 seconds. If the engine compartment temperature is still > 185 degrees F after this time, the fan remains on for a further 30 seconds."

LordVicious

Awesome info Loren (as always.) I live in central Florida, next to the surface of the sun, and have never seen or heard my engine compartment fan come on. I guess now I know why.

Macster

The Boxster's engine compartment purge fan comes on occasionally. I can go months during the cooler time of the year without hearing it but a week or so ago we had our first hot spell and with daytime temps in the mid to high 80s running around town I'd hear the compartment fan come on.

The times in the past when I've had an OBD2 data reader connected to the car the intake air temp was 135F. This was the temperature after the car had sat a while and had time to heat soak which I assumed was the trigger temp.

One time in southern AZ the fan ran all the time in 116F heat.

Now a kind of funny thing about the Boxster is that if the car is locked -- which it almost always is if I'm not in the car -- the fan doesn't come on when the car is parked and the engine is off. But a few times I have stopped the car, turned off the engine and let the car sit a few minutes unlocked while I dashed to the house for something. Upon returning to the car the fan was running.

The Turbo's engine compartment purge fan runs more often and even on milder days. Obviously heat load added by the larger output engine, larger/more massive exhaust system along with those turbos contributes to this.

Now the Turbo's engine compartment purge fan runs even when the engine is off. During this same hot spell a while back I'd come to the Turbo after leaving it parked up for a while and hear the fan running.

I'm not trying to be argumentative but I suspect the fan in your car, all of the cars of the other posters, runs more often than you think.

Regardless I see no reason to disconnect it. If it comes on at all it is removing heat from an area from which heat needs to be removed and from which continued exposure to elevated heat levels is not good.

trendy996

The rear vented spoiler removes the heat well enough with it removed. Just like how the front rad fans hardly kick on and they get cooled well enough by moving air when the car is in motion. My car hardly gets hot. I'd be the last person to do so if I really felt I would cause damage to a 10k engine. When the other person mentioned the 180ish temp to trigger it, that temp(180) triggers the flashing light on the temp gauge and the fan will be on at that engine bay temp.

Macster

There is while the car is moving, that is moving at a speed which forces air flow through the engine compartment, but there is also when the car is stopped.

Yesterday was 90F and the Boxster's compartment fan was on quite a bit once the car was up to temp as I was running around town doing errands.

While my Boxster's engine compartment fan doesn't run when the car is locked more than once the other day when I got back into the car and started the engine the engine compartment fan came right on. This is from the considerable heat load the engine sheds after is shut off.

Also, while my Boxster's engine compartment fan doesn't run when the car is locked the Turbo's does.

More than once I have come back to my Turbo, sometimes nearly 30 minutes after shutting it off, and found the engine compartment fan running.

In fact just the other day I had the manager at the assisted care facility where my parents are tell me my "car was running".

While I never leave the engine running when I'm not in the car I thought maybe I was so distracted I forgot so I walked outside and heard the engine compartment fan running. This was some minutes after I parked the car.

The engine compartment essentially turns into an oven -- the heating element is the hot engine and its even hotter exhaust system (the converters run at nearly 1000F) -- when the hot engine is shut off. Why anyone would disable the engine compartment fan is beyond me.

mmahon04

Macster, I think comparing a 2.7L Boxster and 996 Turbo and their cooling routines is not totally relevant to a 996 Carrera.

I would refer everyone to Loren's comment. It should not (and will not) frequently kick on. Just look at the requirements for it to be triggered; it has to be mighty hot to have it operate. It's generally referred to as a purge fan as a reason. I think the thermal equilibrium for the engine bay is generally below 175oF (ambient temperature dependent, obviously), so to hit one of the two criteria, it's has to be scorching. The only time mine has operated was prior my cooling system upgrades, in stop-and-go traffic for ~30 minutes on a 90+ degree day.

Shark Attack

Thank you for the responses. I guess I need to find out if its running. My car used to run a little cooler and I would like to know why. Think this may be it.

Thundertub

Another one of those "Duh!" facts is that if you use a car cover, do not throw it over the car for at least an hour after you have parked it. The cover traps the hot air in the engine compartment and also blocks the cool air trying to be brought in by the fan.

Same applies to pulling into the garage and closing the garage door immediately after running the car on a hot day (unless you park in a "climate controlled" garage).

Cuda911

I'm finding it a total mystery as to when my fan kicks on. Sometimes I drive the car hard, and no fan. Like Macster, last week someone told me that I left my car running. It was about 30 minutes after I had parked it. So, had to put down my margarita, clamber out of the spa, and hoof it over to the car merely to find that the purge fan was running (it stopped about 30 seconds later).

Last night I was re-adjusting the memory seats and mirrors, so I had the car running at idle for about 10 minutes in the garage. Then the fan kicked on and off several times over the next 30 min.

Is there anything about this fan behavior that should have me concerned?