Hi all, my car's been running hot, around 200+F I think. Anyway, I noticed the fan on the engine compartment is not running. The two fans up front do appear to run normally.
So I heard unplugging the ambient temperature sensor should cause the engine fan to always run, so I unplugged that, started up and no fan.
Any idea what my next step is to fix this fan or determine why it doesn't run?

 

first of all, I don’t think that the fan in the engine bay will affect the engine operating temperature.
the purpose of this fan is to cool the engine bay and usually works after the car is parked, or in heavy traffic.
if your engine is running hot, start with checking the coolant level and make sure the radiators fans are working in both speeds.
it’s very common that the fan resistors go bad and the fans (or one of them) will not work properly.
a duramatric can come in hand as it can activate the fans in both speeds, and can also activate the engine bay fan for diagnostic.
hope it helps.

 

You mean the ambient temp sensor in the front bumper? That will not trigger the engine bay fan. The engine bay fan uses the engine bay temp sensor located between intake plenums 5 and 6 (passenger side Bank 2). The engine bay fan rarely runs if everything is right. There are specific parameters for the engine bay fan to run, of which I don't remember. You can look it up with a search. You can test/trigger the engine bay fan with Durametric or PIWIS. Check with your dealer or Indy, or a friend, or a fellow PCA member.

 

The radiator fans should be running on high if you turn on the A/C, so you could test them that way. My car always ran cooler with the A/C turned on.

 

Yeah...but I think he is wondering why the engine compartment fan is not working. Maybe the OP needs to pop in and clarify.

 

From the service manual (my 2003 behaves just like this - I've gone back into the hot garage and will find it on although I left the car with it off)....

"Switch-on conditions for engine compartment fan (this fan pulls air into the engine compartment from the top) 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."

See this thread:

Deck lid fan - Page 2 - Rennlist - Porsche Discussion Forums

 

For a street car, 200F is fine. The engine is designed to run well up to 96-100C in stop and go traffic where airflow is low. Water boiling at 100C (212F) will not cause any cooling issues on your engine or oil problems with your car because coolant extends the upper limit by a fair amount. By that time, the fans are on full blast.

The rear fan doesn’t contribute much to overall cooling, but it will keep the engine bay from getting too hot. Mine comes on rarely.

 

The fans with the AC button come on low speed, unless the pressure in the AC circuit goes above 16-bar. This happens on my car when it’s really hot outside. If your fans come on high right away, someone may have bypassed the resistors as a ‘mod’ or else the resistors have failed.

 

Resistor fail on fan unit.. Its a thing... I did the retrofit of Aluminum aftermarket 200Watt resistors on mine , the Porsche part is stupid design and stupid expensive.

OOPS wrong fan ignore..

 

Having the same issue. Need to check the engine compartment for the sensor, but car is located at another location out of fear of overheating as the temps increase.

Temp gauge sits comfortably at 180 moving but as soon as stop and go hits, I am sitting up to 200, but it drops as soon as I get moving.

Going to run the AC next I am with the car and check for the sensor. Checked Bentley guide, and there is no clear picture or diagram as to where to exactly find it. I recently had my second loss at getting to the oil pressure sensor switch, so I'd really like to get at what I need to look at without guessing. Ordered the 101 Projects book as well since I hear that is well laid out with extensive reference photos and diagrams per job.

 

Nothing wrong with 200F. Radiator fans come on at 206F without AC. Engine compartment fan activated at 216F coolant temp or 176F compartment temp.

 

How do you know it’s actually 200? On my car, the last white line activates low-speed fans, so that last white line isn’t red and it’s not dangerous to be there, IMO.

 

I am still learning what the heat tolerances are... So I apologize if this sounds like a knee-jerk concern, however, last thing I want to do is assume all is okay when I know I am due for the radiator change out in two weeks.

Posting pics from the last week or so. Stop and go with outdoor temps ranging from 60-85F





And yes, I am changing out the oil pressure sensor switch today, third attempt at that... Go me.

 

I dont see any problem with your dash. the coolant temp is right and is no where neer when the fans turn on. U need a scanner that can read the water temp. Thet r a lot cheaper to buy then throwing parts at your car that u dont need. Go buy a durametric.....im only the 10th guy here that has told u this.


Also about your thread title.... "engine fan" usually reffers to the fan under the rear deck lid. U r reffering to the radiator fans.

 

Yeh I’ve been accustomed to the engine fan running on a few occasions when hotter but dawned on me after your post that it was likely due to the AC running.

For stop and go coolant temps, with the caveat I have a small forward passenger rad leak but am not pumping coolant into the car to keep the tank up, what’s the general tolerance? My Cayman never budged and my F80 was consistently pegged to around normal temp even after HPDEs.

Obviously have more reading to do and apologize for the stupid assumptions.