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Discussion summary
YOUR RESEARCHDeck lid fan
Leading reported evidence
Install on the intake manifold
Performed · outcome unconfirmed
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0
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0
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1
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The fan is not triggered by the engine temperature, but by a dedicated sensor installed on the intake manifold.
Leading evidence: 'Install on the intake manifold' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Install on the intake manifold' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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I said “it use to” because I don’t see it working anymore after I installed a Techart rear wing.
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Yes, that description is definitely from Bosch and this same Sensor under a Bosch part number and is used on some Chevy's on the air-box or air intake boot ( with a different MAF Sensor) ..
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Suggestion
When I first got my car the fan would run almost every time I drove it.
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Yes, that description is definitely from Bosch and this same Sensor under a Bosch part number and is used on some Chevy's on the air-box or air intake boot ( with a different MAF Sensor) ..
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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).
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?
From the service manual...
"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."
Yes, that description is definitely from Bosch and this same Sensor under a Bosch part number and is used on some Chevy's on the air-box or air intake boot ( with a different MAF Sensor) ..
The " function description" would be correct for some Chevy's , but under the Porsche 996 part # and "usage" is not correct...AT ALL ..
I've got to check if my fan kicks on, ever. I'll crawl under and get a flashlight on the sensor. Presumably though if it were missing or faulty a cel would be triggered? I need to invest in durametric, and stop guessing at these things. I guess.
