Does anyone know when the fan under the deck lid is supposed to kick on? At warmer temps I looked under the lid and the fan was not running. I could hear the radiator fans running though. The temp was about where it is in the below pic. 99 C2

 

The fan is not triggered by the engine temperature, but by a dedicated sensor installed on the intake manifold.
the sensor is measuring the ambient temperature at the engine compartment.
in my car it use to kick in few minutes after I parked the car after a drive on a hot day.
I said “it use to” because I don’t see it working anymore after I installed a Techart rear wing.
at first I thought maybe it went bad, but it works fine when I activate it using the Durametric.
so it’s either the wing is providing better ventilation to the engine bay, or the sensor is bad (which I doubt).

 

any chance you can explain or show a pic where the sensor is located?

 

https://www.pelicanparts.com/techart...ne_Sensors.htm

It's the first pic.

 

If any of these sensors are not working properly, would it throw any codes?

 

This is from the FCP Euro website.
I guess this sensor is responsible for other functions beside activating the fan.

 

Mine is the same, it only comes on after a drive on a hot day.

 

I just cleaned out the ducts in front bumper. These pieces were wedged in the back corners. Not sure if this will make a difference, but we’ll see.

 

Has anyone wired the deck lid fan to manually switch it on in hot weather? is it even worth doing?

 

Just to keep Technical accuracy in a Technical forum..


That "function description" for that part # Sensor is WRONG !!!

The description is describing the function of the Air Charge Temperature Sensor that is an integral part of the MAF Sensor...It is made into the MAF Sensor and has separate wires for it apart from the air flow sensing unit..

The Sensor in question here ( and the part # referenced above) is for the Engine Compartment Air Temp Sensor, it's only function is to sense the air temp of the engine compartment and report it to the DME ,if above 150F the DME will turn on the deck lid fan ., If the engine compartment air temp rises above 175F the DME will " slow flash" the coolant warning light..

 

When I first got my car the fan would run almost every time I drove it. Started investigating and found the sensor hanging by its wire between the engine and the exhaust. The bung was missing so I ordered one and wouldn't you know it while inserting the new bung and sensor I found the old bung lying on the engine. End result, no more running compartment fan.

 

No need to as it only vents the engjne bay and usually only when stopped or low speeds when there is little air flow. When the sensor is in its correct place the system works fine.

 

thank you for clearing that out.
I was also under the impression that this sensor is responsible for the fan only before I came across this page.
great info.

 

I know some have done the rear fan when doing the high speed radiator fan toggle mod, IIRC it didn't seem to have any measurable impact on coolant/oil temps, and is more of a pain to get to, so it didn't seem worth it.

 

On Turbos there are two fuses for the engine compartment blower (as Porsche calls it). One is for the DME to turn on the fan as needed, the second makes the fan run all the time the key is on at a slower speed.
Fuse B4 = fuse for DME to control the fan
Fuse C5 = fuse to run the fan all the time at a slower speed.
Does this exist on the NA cars?