crashclint

Pins were easy to get out of the plug gently using a small pick. I reversed the polarity and it is sucking air. I am surprised by how much air movement I can feel underneath the rear end of the car.

Rubik

Now you know for sure if she sucks or blows.

islaTurbine

How can you check to see if your fan is operating properly without a Durametric?

I just ran a blow dryer on high on the sensor probe while the engine was idling at 180° and the fan never came on once. I don't recollect ever hearing it operate since I've owned the car and we have some damn hot weather here in DFW.

fpb111

it looks like some of the aftermarket folks are confused also.

"So I get an error message on the first hot day of the year with me in the car...engine cooling fan potential failure. I go back and notice it is spinning fine, heat sensor is in place, coolant level is normal/correct, no cracks, but the air is now blowing up and out...pre-new harness it was blowing in "I think."

So I called my harness vendor. M.A. Shaw. Super guy. His harness is 50% of OEM and of the same quality. It is very, very high quality. Perhaps better than OEM. He happened to have gotten an email from me on this subject yesterday and had lunch with four Porsche mechanics and they all told him on the 996TT the air blows out.

So, I wanted to know if you guys could help me out and say if the decklid air fan blows in or out...probably best to check after a drive when it is idling...it is not very efficient so you can be fooled but a piece of paper over the vents makes it pretty obvious either way. Mr. Shaw suggested maybe Porsche changed things year to year. Hence the format of the poll is by year and in/out.

Needless to say, my error message went away with the new fan direction (I cut the harness, spliced, and heat tubed it last night). And the fan ran "less long" after driving... It could be another issue with my car, but this question comes up from time to time and I'd like this thread to be data for the rest of the board to use.

Just think of the fabspeed cold air kit...it says the "fan blows cold air directly at the filter".....but I want to be sure as he feels 4 mechanics are telling him the opposite. It makes little sense to me that you'd draw the air past the manifolds, turbos, and exhaust. But, I suppose this does let more water into the engine (not something Porsche seems to be worried about historically)."

kalyan

On my TT, it sucks air from above and blows over the engine. Last week, it was pretty hot here and after I pulled into the garage and shut off the engine, I heard the fan run. I put my palm over the rear vents on the deck lid and I could definitely feel air being sucked in. I always had thought that the air would be blown up to remove the hot air (since hot air rises), but I guess, the air to be sent down if you are driving (aerodynamics reason?) and the fan needs to run.

fpb111

I think you are talking about the SAI pump. We are talking about the vent fan on the deck lid.

islaTurbine

Figured it out. If you unplug the harness at the base of the temperature sensor while the engine is running (mine was at 180°F) then the compartment fan will come on after about 3 seconds.

ZX9RCAM

Thank you, you are probably right.

That means my fan does not come on I guess.

dporto

^Same here^ Maybe not as hot as DFW but I've never seen or heard my engine compartment fan operate. This being said, my temp gauge has never climbed above the left edge of the 0 in 180 either (I figure the temp to be around 190 - 200 degrees F ?)... We've had ambient temps between 85 - 90F this summer, so she warms up pretty quickly...

5CHN3LL

It's very seldom that the purge fan goes on. With my MKII aero wing (which allows for a lot of airflow when the car is off), the fan may have gone on a total of 2 or three times over the past 3 years. I've definitely turned it on more times with Durametric than it's run on its own.

So...I wouldn't start throwing parts at the car if you're not hearing the purge fan come on after a hot drive.

crashclint

My fan comes on quite a bit with temps in the mid 90s here in the Raleigh, NC area. Since I switched the polarity to be correct it doesn't run as long but if I am in bumper to bumper traffic it comes on. I have a tiptronic trans so not sure if that has anything to do with it or not, do the tips produce more heat?

5CHN3LL

Well, mid 90's is about 15 degrees hotter than what my 996 is used to - so I can't say if it's the ambient temp or the tiptronic...

dporto

"So...I wouldn't start throwing parts at the car if you're not hearing the purge fan come on after a hot drive."

I don't know if you're specifically responding to me or not... I've had the car since Oct. '14, so no I don't plan on throwing parts at it - more like trying to figure out if the fan does indeed "work"...Like I said previously, I believe the engine temp is within a "normal operating range" so it's not like I'm freaking out about it - just wondering... Thx

DBJoe996

Either trigger it with Durametric or run a hot lead to it from the + jumper point in the engine compartment. Florida high 90's, hot, and the purge fan hardly ever runs...but I know it works.

dporto

Yeah...no Durametric here yet... I'll try the "hot lead" test just to ease my mind