Question about engine compartment cooling fan

[up4speed]

I have a 2001 911 TT and I'm still new to the car and trying to figure out what is normal, and what is not.

After reading hundreds of posts regarding the engine compartment fan, I still don't know if mine is behaving normally. It's possible that mine may be different because my car is not 100% stock anymore, and I think that may causing confusion for me. I was under the impression that the fan should be off until the engine bay reaches a certain temperature while the engine is running (I think it was 170 deg.), and when the engine and key are off, it turns on if the engine compartment gets up to about 140 degrees or something like that.

The way mine is operating:
Cold engine Key on, engine off - fan is off (that's good)
Hot engine, engine off - fan kicks on when heat builds up (that's good)
BUT.......
Cold engine, fan starts immediately when engine is started and runs the whole time that the engine is running. That's the confusing part because I thought it supposed to kick on only when the engine bay reaches a certain temperature and cycle off and on as needed to keep the engine bay temps down below that 170 degree mark.

If my car is not behaving normally, the answer may be in the wiring harness, but would like confirmation from someone who knows for sure.

My spoiler was stuck in the down position so I installed the fixed spoiler kit from e-bay. The instructions said to install the fixed spoiler harness in order to prevent the error light from coming on. I installed the harness # 996-612-070-04. Possibly this harness was designed for the GT cars and some how keeps the fan on?


Any ideas?

 

[JFP in PA]

I have a 2001 911 TT and I'm still new to the car and trying to figure out what is normal, and what is not.

After reading hundreds of posts regarding the engine compartment fan, I still don't know if mine is behaving normally. It's possible that mine may be different because my car is not 100% stock anymore, and I think that may causing confusion for me. I was under the impression that the fan should be off until the engine bay reaches a certain temperature while the engine is running (I think it was 170 deg.), and when the engine and key are off, it turns on if the engine compartment gets up to about 140 degrees or something like that.

The way mine is operating:

Cold engine Key on, engine off - fan is off (that's good)

Hot engine, engine off - fan kicks on when heat builds up (that's good)

BUT.......

Cold engine, fan starts immediately when engine is started and runs the whole time that the engine is running. That's the confusing part because I thought it supposed to kick on only when the engine bay reaches a certain temperature and cycle off and on as needed to keep the engine bay temps down below that 170 degree mark.

If my car is not behaving normally, the answer may be in the wiring harness, but would like confirmation from someone who knows for sure.

My spoiler was stuck in the down position so I installed the fixed spoiler kit from e-bay. The instructions said to install the fixed spoiler harness in order to prevent the error light from coming on. I installed the harness # 996-612-070-04. Possibly this harness was designed for the GT cars and some how keeps the fan on?

Any ideas?

 

Did the fan work normally before you installed the fleabay wiring harness? Does it work correctly if you remove the harness?

[up4speed]

I have a 2001 911 TT and I'm still new to the car and trying to figure out what is normal, and what is not.

After reading hundreds of posts regarding the engine compartment fan, I still don't know if mine is behaving normally. It's possible that mine may be different because my car is not 100% stock anymore, and I think that may causing confusion for me. I was under the impression that the fan should be off until the engine bay reaches a certain temperature while the engine is running (I think it was 170 deg.), and when the engine and key are off, it turns on if the engine compartment gets up to about 140 degrees or something like that.

The way mine is operating:

Cold engine Key on, engine off - fan is off (that's good)

Hot engine, engine off - fan kicks on when heat builds up (that's good)

BUT.......

Cold engine, fan starts immediately when engine is started and runs the whole time that the engine is running. That's the confusing part because I thought it supposed to kick on only when the engine bay reaches a certain temperature and cycle off and on as needed to keep the engine bay temps down below that 170 degree mark.

If my car is not behaving normally, the answer may be in the wiring harness, but would like confirmation from someone who knows for sure.

My spoiler was stuck in the down position so I installed the fixed spoiler kit from e-bay. The instructions said to install the fixed spoiler harness in order to prevent the error light from coming on. I installed the harness # 996-612-070-04. Possibly this harness was designed for the GT cars and some how keeps the fan on?

Any ideas?

Did the fan work normally before you installed the fleabay wiring harness? Does it work correctly if you remove the harness?

[up4speed]

I have a 2001 911 TT and I'm still new to the car and trying to figure out what is normal, and what is not.

After reading hundreds of posts regarding the engine compartment fan, I still don't know if mine is behaving normally. It's possible that mine may be different because my car is not 100% stock anymore, and I think that may causing confusion for me. I was under the impression that the fan should be off until the engine bay reaches a certain temperature while the engine is running (I think it was 170 deg.), and when the engine and key are off, it turns on if the engine compartment gets up to about 140 degrees or something like that.

The way mine is operating:

Cold engine Key on, engine off - fan is off (that's good)

Hot engine, engine off - fan kicks on when heat builds up (that's good)

BUT.......

Cold engine, fan starts immediately when engine is started and runs the whole time that the engine is running. That's the confusing part because I thought it supposed to kick on only when the engine bay reaches a certain temperature and cycle off and on as needed to keep the engine bay temps down below that 170 degree mark.

If my car is not behaving normally, the answer may be in the wiring harness, but would like confirmation from someone who knows for sure.

My spoiler was stuck in the down position so I installed the fixed spoiler kit from e-bay. The instructions said to install the fixed spoiler harness in order to prevent the error light from coming on. I installed the harness # 996-612-070-04. Possibly this harness was designed for the GT cars and some how keeps the fan on?

Any ideas?

Did the fan work normally before you installed the fleabay wiring harness? Does it work correctly if you remove the harness?

The harness was not a fleabay harness! It was an OEM Porsche harness that is designed for the fixed spoiler cars with a brake light. The "fleabay" part was the kit that takes the stock spoiler, removes the finicky hydraulics and sets the spoiler in a fixed position.

Unfortunately I'm very new to the car and didn't take notice to it beforehand. I guess if no one can answer the question of whether ther fan is spinning when their car is started cold, I may have to put back the original harness to see how it behaves. I was trying to avoid that because the harness is already in my attic, plus it's a pain to unclip the connector because it's deep in the fender where it's located.

[Loren]

996 612 070 04 is an Aerokit harness for a normally aspirated (narrow body) 996.

According to the TSB for the 996TT Aerokit the correct wiring harness for an  Aerokit 996TT is: 996 612 070 30

[Dus10R]

Personally wouldnt be too concerned. I had a Ducati years back and they notoriously ran at a really high temp, not overheat just really high, so installed a manual switch on the fan and would turn it on soon after it reached a normal temp and it would keep the engine temps down to a normal level. If i didnt turn it on and let it get up to normal high temp and then turned the fan on, it was too late, the fan couldnt bring the temp back down again. Even on my current 997 I notice if I kick the spoiler up shortly after starting out it keeps the oil temps slightly cooler for longer. I dont think the fan kicking on is bad, the car will reach its proper op temp with no problem and the fan just may keep it there instead of letting it heat soak and going higher. Its better to have it stuck on, then off. Dont remember my old Turbo doing that though. Dont recall the fan kicking on when starting it cold. Have Durametric? If not get one.

[X-UFO]

The 996TT fan works all of the time as soon as the engine starts whether hot or cold.

 

I have a 996TT after 5yrs of 996C2 ownership which was different. The engine compartment fan on other models only comes in when the engine compartment reaches a certain temperature.

 

So, it's normal for it to be on all of the time on a 996TT.

[Loren]

For the 996TT (from the Porsche Service Information Book 2001):

 

"Two-speed compartment scavenging blower

 

To prevent components from heating up excessively especially as a result of radiated heat from the exhaust system, the fuel pump relay immediately activates the engine compartment scavenging blower (stage 1) if the engine is running at idling speed or if the ignition is switched on ( for longer

than 1 sec.). Stage 2 is actuated by the engine compartment temperature sensor.

 

Caution! Safety note:

Special care must be taken when working on components in the engine compartment with the engine running or with the ignition switch on.

 

Switching stages:

 

1st stage:

Ignition ON (for longer than 1sec.) or engine running (actuated by fuel pump relay via booster resistance cable).

 

2nd stage:

At coolant temperature of approx. 105 °C or engine compartment temperature of approx. 78 °C (OFF at approx. 60 °C). 

 

After-run phase:

Requirement: Engine compartment temperature with ignition OFF > 25 °C

 

After-run ON:

For 3 minutes at engine compartment temperature > 78 °C. The switch-on condition of > 78 °C is then checked every 10 seconds.

The after-run phase is active for max. 40 minutes."

[up4speed]

996 612 070 04 is an Aerokit harness for a normally aspirated (narrow body) 996.

According to the TSB for the 996TT Aerokit the correct wiring harness for an  Aerokit 996TT is: 996 612 070 30

I purchased the 996 612 070 04 because that was the harness that was listed in the instructions for the fixed wing kit.  Maybe the "proper" harness for my car doesn't have a lead for the third brake light?  If it does, I wonder why the instructions didn't refer to that harness.

 

The 996TT fan works all of the time as soon as the engine starts whether hot or cold.

 

I have a 996TT after 5yrs of 996C2 ownership which was different. The engine compartment fan on other models only comes in when the engine compartment reaches a certain temperature.

 

So, it's normal for it to be on all of the time on a 996TT.

Ok great!  I was worried because there seems to be so many different stories on what is proper for the car.

 

 

For the 996TT (from the Porsche Service Information Book 2001):

 

 

1st stage:

Ignition ON (for longer than 1sec.) or engine running (actuated by fuel pump relay via booster resistance cable).

 

2nd stage:

At coolant temperature of approx. 105 °C or engine compartment temperature of approx. 78 °C (OFF at approx. 60 °C). 

 

After-run phase:

Requirement: Engine compartment temperature with ignition OFF > 25 °C

 

After-run ON:

For 3 minutes at engine compartment temperature > 78 °C. The switch-on condition of > 78 °C is then checked every 10 seconds.

The after-run phase is active for max. 40 minutes."

 

The strange part is that my fan works as described above except for the key on engine off situation.  My fan does not come on simply by turning the key to the on position.  The car must be started for the fan to start spinning.

Edited October 9, 2014 by up4speed

[EleCTriCT]

Can anyone help identify the Engine Compartment Fan Temp Sensor Location on the Twin Turbo?

 

It must be a little more hidden than on the NA cars.

 

Thanks.

[JFP in PA]

Can anyone help identify the Engine Compartment Fan Temp Sensor Location on the Twin Turbo?

 

It must be a little more hidden than on the NA cars.

 

Thanks.

Right side of the engine bay, behind the recirculation fan, near the oil fill cap.

[jpflip]

Just beside the steering pump reservoir....

[DaveCarrera4S]

My fan does not come on with the key in the on position. It's an '02 turbo. Wonder if the ECU program was changed after '01 model year? I believe it only comes on if the temp sensor is above a certain "hot" temp.

[EleCTriCT]

Thank you. In my situation the sensor was lying on the block - most likely getting to much heat.

 

Cheers

[up4speed]

My fan does not come on with the key in the on position. It's an '02 turbo. Wonder if the ECU program was changed after '01 model year? I believe it only comes on if the temp sensor is above a certain "hot" temp.

Look in your fuse box.  Look at fuse #5A.  If it is missing or blown, the cars fan will come on only when the engine gets hot.  If the fuse is in there and good, it will turn on when the car is started.

I haven't figured out why some cars have the fuse and some don't, but it seems that the different cars from different areas are set up differently.  My best guess is that maybe if the car is from a colder area, the fuse is pulled.  I would imagine if  the car sat parked and snow got packed in the fan preventing it from spinning, that could be a bad thing.  Those cars are probably set up to warm up and melt the snow, then spin the fan.  Not sure, but that's my best educated guess.

Edited May 5, 2015 by up4speed

[DaveCarrera4S]

My fan does not come on with the key in the on position. It's an '02 turbo. Wonder if the ECU program was changed after '01 model year? I believe it only comes on if the temp sensor is above a certain "hot" temp.

Look in your fuse box.  Look at fuse #5A.  If it is missing or blown, the cars fan will come on only when the engine gets hot.  If the fuse is in there and good, it will turn on when the car is started.

I haven't figured out why some cars have the fuse and some don't, but it seems that the different cars from different areas are set up differently.  My best guess is that maybe if the car is from a colder area, the fuse is pulled.  I would imagine if  the car sat parked and snow got packed in the fan preventing it from spinning, that could be a bad thing.  Those cars are probably set up to warm up and melt the snow, then spin the fan.  Not sure, but that's my best educated guess.

I will check the fuses. The engine lid light also is sporadic in operation.

[up4speed]

 

 

My fan does not come on with the key in the on position. It's an '02 turbo. Wonder if the ECU program was changed after '01 model year? I believe it only comes on if the temp sensor is above a certain "hot" temp.

Look in your fuse box.  Look at fuse #5A.  If it is missing or blown, the cars fan will come on only when the engine gets hot.  If the fuse is in there and good, it will turn on when the car is started.

I haven't figured out why some cars have the fuse and some don't, but it seems that the different cars from different areas are set up differently.  My best guess is that maybe if the car is from a colder area, the fuse is pulled.  I would imagine if  the car sat parked and snow got packed in the fan preventing it from spinning, that could be a bad thing.  Those cars are probably set up to warm up and melt the snow, then spin the fan.  Not sure, but that's my best educated guess.

I will check the fuses. The engine lid light also is sporadic in operation.

 

The light is a whole other issue.  That is most likely one of a few things.  I would start with the bulb and check that it's not on it's way out (maybe even change it just to be sure.  Sometimes a bulb won't look bad when it actually is. It's cheap insurance).  I would also make sure that the wiring harness is plugged in tightly (It's the same harness for the fan, spoiler and light), it's plugged in on the passenger side on the inside of the right rear fender.  If it's not either of those, It may be a flaky switch (I think it's incorporated in the lock mechanism, but not sure because I didn't look).

Please let us know how you make out.

[AJRN]

On a slight side note - my car 2002 Turbo (US Spec) has started giving me a warning message (triggered at 180º) on the dash saying "Failure of Engine compartment Blower".... except that the fan is blowing and apparently operating normally. It will continue to run with the engine off and will then shut itself off after a few minutes.

Confusing....

[up4speed]

On a slight side note - my car 2002 Turbo (US Spec) has started giving me a warning message (triggered at 180º) on the dash saying "Failure of Engine compartment Blower".... except that the fan is blowing and apparently operating normally. It will continue to run with the engine off and will then shut itself off after a few minutes.

Confusing....

You are correct, it is confusing.

I wonder if the engine compartment temp sensor is bad and the fan is defaulting to "on" causing the symptoms that you are seeing?  In other words the computer is giving the message that it's defective, but to you it looks normal since the fan is on.

Does your fan stay running as soon as your engine is shut down?  If I remember correctly, the fan will go off, then a few minutes later as the engine compartment heats up, the fan will come on.

Does your fan stay on even if the engine is not fully hot, then shut down? 

[AJRN]

I assume that the sensor must be working as the fan switches on and off - whether the engine is running or not. It's the cause of the error light that's got me confused. Unless it's something like a sticky microswitch for the fan or something....

[DaveCarrera4S]

 

 

 

My fan does not come on with the key in the on position. It's an '02 turbo. Wonder if the ECU program was changed after '01 model year? I believe it only comes on if the temp sensor is above a certain "hot" temp.

Look in your fuse box.  Look at fuse #5A.  If it is missing or blown, the cars fan will come on only when the engine gets hot.  If the fuse is in there and good, it will turn on when the car is started.

I haven't figured out why some cars have the fuse and some don't, but it seems that the different cars from different areas are set up differently.  My best guess is that maybe if the car is from a colder area, the fuse is pulled.  I would imagine if  the car sat parked and snow got packed in the fan preventing it from spinning, that could be a bad thing.  Those cars are probably set up to warm up and melt the snow, then spin the fan.  Not sure, but that's my best educated guess.

I will check the fuses. The engine lid light also is sporadic in operation.

 

The light is a whole other issue.  That is most likely one of a few things.  I would start with the bulb and check that it's not on it's way out (maybe even change it just to be sure.  Sometimes a bulb won't look bad when it actually is. It's cheap insurance).  I would also make sure that the wiring harness is plugged in tightly (It's the same harness for the fan, spoiler and light), it's plugged in on the passenger side on the inside of the right rear fender.  If it's not either of those, It may be a flaky switch (I think it's incorporated in the lock mechanism, but not sure because I didn't look).

Please let us know how you make out.

 

Here is the result of the light.  The double wire was sliced through clean about 1" from the connector.  Why?  No frickin idea.  stripped the wires back and put a wire connector between each - works like a charm... Now back to the fan issue.

[up4speed]

 

 

 

 

My fan does not come on with the key in the on position. It's an '02 turbo. Wonder if the ECU program was changed after '01 model year? I believe it only comes on if the temp sensor is above a certain "hot" temp.

Look in your fuse box.  Look at fuse #5A.  If it is missing or blown, the cars fan will come on only when the engine gets hot.  If the fuse is in there and good, it will turn on when the car is started.

I haven't figured out why some cars have the fuse and some don't, but it seems that the different cars from different areas are set up differently.  My best guess is that maybe if the car is from a colder area, the fuse is pulled.  I would imagine if  the car sat parked and snow got packed in the fan preventing it from spinning, that could be a bad thing.  Those cars are probably set up to warm up and melt the snow, then spin the fan.  Not sure, but that's my best educated guess.

I will check the fuses. The engine lid light also is sporadic in operation.

 

The light is a whole other issue.  That is most likely one of a few things.  I would start with the bulb and check that it's not on it's way out (maybe even change it just to be sure.  Sometimes a bulb won't look bad when it actually is. It's cheap insurance).  I would also make sure that the wiring harness is plugged in tightly (It's the same harness for the fan, spoiler and light), it's plugged in on the passenger side on the inside of the right rear fender.  If it's not either of those, It may be a flaky switch (I think it's incorporated in the lock mechanism, but not sure because I didn't look).

Please let us know how you make out.

 

Here is the result of the light.  The double wire was sliced through clean about 1" from the connector.  Why?  No frickin idea.  stripped the wires back and put a wire connector between each - works like a charm... Now back to the fan issue.

 

 

 

That's great news that it's something simple!

Now I wonder why it's cut?  Is it possible that the light was staying on and the prior owner just cut it (instead of fixing it properly) so it didn't kill the battery?

[DaveCarrera4S]

My fan does not come on with the key in the on position. It's an '02 turbo. Wonder if the ECU program was changed after '01 model year? I believe it only comes on if the temp sensor is above a certain "hot" temp.

Look in your fuse box.  Look at fuse #5A.  If it is missing or blown, the cars fan will come on only when the engine gets hot.  If the fuse is in there and good, it will turn on when the car is started.

I haven't figured out why some cars have the fuse and some don't, but it seems that the different cars from different areas are set up differently.  My best guess is that maybe if the car is from a colder area, the fuse is pulled.  I would imagine if  the car sat parked and snow got packed in the fan preventing it from spinning, that could be a bad thing.  Those cars are probably set up to warm up and melt the snow, then spin the fan.  Not sure, but that's my best educated guess.

I will check the fuses. The engine lid light also is sporadic in operation.

The light is a whole other issue.  That is most likely one of a few things.  I would start with the bulb and check that it's not on it's way out (maybe even change it just to be sure.  Sometimes a bulb won't look bad when it actually is. It's cheap insurance).  I would also make sure that the wiring harness is plugged in tightly (It's the same harness for the fan, spoiler and light), it's plugged in on the passenger side on the inside of the right rear fender.  If it's not either of those, It may be a flaky switch (I think it's incorporated in the lock mechanism, but not sure because I didn't look).

Please let us know how you make out.

Here is the result of the light.  The double wire was sliced through clean about 1" from the connector.  Why?  No frickin idea.  stripped the wires back and put a wire connector between each - works like a charm... Now back to the fan issue.

 

 

That's great news that it's something simple!

Now I wonder why it's cut?  Is it possible that the light was staying on and the prior owner just cut it (instead of fixing it properly) so it didn't kill the battery?

No, as it was working intermittently for me before it finally quit. I think the wires must have been sheared off by the electric lock mechanism some how.

[up4speed]

Dave,

I forgot it was intermittent.

Good job finding and fixing it!

[DaveCarrera4S]

Ok, drove home from work yesterday 22 miles - freeway 80 mph plus, hot out 90 F.  Fan not running when I pulled into garage, but later my wife asked if I left the car running in the garage.  I jumped up to find the fan whirring away.  So I guess it works, at least with the temp sensor over the engine.  Strange though that I have both fuses in the fusebox.  I thought with both, the fan comes on after 1 sec with ignition on - fuel pump running.