I'm sorry, I have no idea how to tell unless it reports a code that isn't sufficient enough to trigger a service warning but is readable from the diagnostic port. Even then the car's diagnostics may not be able to tell the difference.

Please NOTE: Don't trust me to have gotten the part numbers, costs, or possibilities below correct. Please verify yourself or get the pros to take care of it.

Looking on the AutoAtlanta web site, it appears the fan is $363 and the controller is $193 (part seems to be 99761843602, superseded with 99761843604). I also see some of these used (salvaged) from much less on eBay.

Looking at the photo of the controller on eBay (http://www.ebay.com/itm/09-Porsche-9...-/141104967643), and here (http://www.a-neufeld.de/Porsche-911-...02-99761843602), I was hoping that the connectors for left and right would be the same and you could try plugging them in the other way around (left to right and right to left), but they are not. If the problem stayed on the same side then it is the fan, if it moved, it would be the controller. If you are clever and safe with jumpers I guess you could try it, but be careful not to short anything out.

If you wanted to gamble, you could try the cheapest possible solution first, the eBay used controller, and see if that fixes it. I don't know where the module is though and how hard it is to get to. The eBay fans seem to be costing a lot more.

 

I was thinking the fan also. I'm not sure if module was going , it would always be on one side. Its always drivers side not coming and passenger full blast. It just so many days in between that problem occurs . I thought it was just debris . It will go on lift next week and get to bottom of it. Can there be any other things involved besides these two . Thanks a lot

 

Cleaning the radiators is all well and good but that does not clear any obstructions that could be jamming up the fan. The fan is behind the radiator. You can access the fan from the wheel well. Before you spend money on it I would suggest try checking to make sure your fan rotates freely.

 

Perhaps a dumb question but is your climate control set to defrost or max?. That can activate the compressor and operate the system at full tilt.

 

I don't believe it would be debris anymore since I went over a week without it happening . I had a few good long drives in between that passenger fan didn't come on full blast .....and I didn't have any climate control on at all....its just weird how it only happened three times in about a month ...

 

Wish I knew what to do to help.............

 

I have almost exact issue, haven't found a fix yet tagging along to see what would be proper fix?

 

Still undetermined... Was at shop last week and a code was there for drivers side fan. Mechanic said when he got to fan he spun it and herd grinding and crunching from a ton of road debris ..He cleaned both fans out and have been driving without any issue . I'm going back next week for brakes and he said he will check to see if a code was thrown again , just in case I didn't here fan kick on while driving . He thinks the debris was what was causing problem , hopefully and if not I'll replace fan...

 

See post #33.

 

Just an update on my issue, I went ahead took front wheels off and openned up the inside fender lining and cleaned/vacumed. Driver side fan had small rock stuck inbetween the blade and base which caused it to not spin; hence passenger fan was running all the time. I went ahead and cleaned both sides and so far have no running fan issue.
hope this helps others who have same/similar issue.

 

I took a picture of the fan last weekend when I was draining my coolant. This is the driver's side looking forward. You can see how a rock or debris could get stuck between the fan and shroud. When one fan jams the other side compensates.

 

^^ funny I also took exact same pictures with my cell phone..but yea it amazes me how rock can get up there and jam the blades..I guess we know we are driving these cars the way they meant to be driven LOL..