A/C Fan Relay -Part 2

[RNajarian]

Last year I replaced the original fan relay in my 2005 V6 Cayenne . . .

2005 Cayenne V6 A/C Fan Relay Replacement

All worked well for nearly a year (2,000 miles), however, recently some odd behavior has developed with my A/C fan.

The system starts out working as expected, but after an unspecified amount of time, the front fans quit, though the rear fans still work and the speed can still be altered faster/slower. At this point the front fans are non op.

If I completely shut down the A/C system for 10 seconds and then turn on the system, it will work again on the HIGHER 2-3 fan settings, anything slower, the front fans will shut down again. If I completely shut down the A/C wait 10 seconds the front fans will work . . .

. . . Then after an unspecified amount of time the front fans will shut down and I need to go through the process of shutting the A/C for 10 seconds and again for an unspecified amount of time it works until the fan stops and I need to go through the shut down process again. It is important to note all the while my rear fans are still working as expected.

HERE is my question; Do you guys think this odd behavior is from a bad relay, less than one year old and 2,000 miles?

I originally thought I bought an OEM unit from our host (in a large 911 order) but after checking receipts it seems that four years ago when I first noticed the A/C fan problem I apparently bought a Chinese Knock off.

Is this relay bad or is my fan shot? I’m planning on picking up a proper relay from our host but I thought I would ask the group for your thoughts.

Thanks

[fintstone]

Had exactly the same problem about 2 years ago on my 2004 Turbo. My front AC fan had been intermittently making a droning noise and cutting out. For months I got by with it working off and on since the rear worked (and the front worked some). It got really hot out in Aug and that motivated me to do something. My rear fan for the back seat worked fine so I assumed the fan was the problem. I pulled it as per directions here (Cayenne "How To Articles" which were very good. Then I reconnected the connector where I could observe the fan and turned on the AC to confirm the diagnosis.

The new fan fixed my problem didn't need the regulator. The job only took about an hour due to the good instructions provided here https://www.pelicanparts.com/techarticles/Porsche-Cayenne/35-ELEC-HVAC_Blower_Fan_and_Regulator_Replacement/35-ELEC-HVAC_Blower_Fan_and_Regulator_Replacement.htm.

[RNajarian]

Thanks for the reply,

That is the next logical step in resolving the problem.

[RNajarian]

I broke out the Durametric and pulled the A/C fault codes . . .

There seems to be three.

Anyone know a reference to completely ID these codes?

Do they point to the front blower motor? Relay? Servo? Actuator? All 4?

Thanks

[RNajarian]

. . . so my internet research reveals this is not an uncommon problem. The Durametric cable revealed problems with the blower regulator (front and back,) which is frustrating since I replaced the relay 4,000 miles ago (albeit with a questionable eBay unit).

I discovered an option with the Durametric which may shed light on my problem. In the A/C section of the program they have actual values for the various components. I started monitoring the front blower regulator and saw the voltage ranged from 0.0v when the system was off to 12.9v at MAX power. What I need to do is hook up the Durametric and monitor the A/C regulator with the system on and wait for it to fail. If the blower fan craps out AND the voltage from the regulator indicates 0.0v then I know the problem is the new regulator/relay. However, if the fan craps out AND the voltage remains at 12.9 then I know the fan is bad. I have noticed the systems fails most often when the ambient temperature is hot.

I should note the fan is NOT making any weird or unusual sounds when it works. My money is the eBay relay is junk . . . We will see

[RNajarian]

For anyone following my plight . . .

I hooked up the Durametric to the car and took her for a spin (actually drove her to the Pasadena dealership to have the recent recall addressed).

The fan would work normally when the cabin was cool. 7:00 am outside/inside temp 70 degrees, but once it heated up a bit 85 degrees outside /90 degrees inside the fan would work for a while then stop. No unusual fan sounds, it just would stop.

Shut the fan completely off wait 15 seconds then it usually comes back on for anywhere from 2 - 10 minutes- then repeat.

The Durametric showed the voltage dropped to zero when the fan quit so I can assume the problem is my “new” eBay regulator .

I’ll keep you guys abreast

[RNajarian]

UPDATE: I replaced the front A/C blower relay in my 2005 V6. Last year I replaced the same part and did so again recently based on the error code my Durametric revealed.

Unfortunately the problem reappeared, interestingly only when the interior of the cabin is hot. If the cabin is cool when I turn on the A/C the blower fan works normally.

I never heard any noises or unusual activity with this blower motor , so that is why I assumed the relay was the bad part. However, it is beginning to appear the bad part is the blower motor, time to visit our Host’s parts page.

Since my relay is new and won’t be replaced I’m hoping not to remove the glovebox To gain access to the blower motor.

Does anyone know if the blower motor can be replaced without removing the glovebox?

There appears to be access if you remove the bottom plastic footwell cover.

Tha ks

[fintstone]

As noted earlier, I am pretty sure it is your blower. You can test it once you remove it.

This is how I removed it:
https://www.pelicanparts.com/techarticles/Porsche-Cayenne/35-ELEC-HVAC_Blower_Fan_and_Regulator_Replacement/35-ELEC-HVAC_Blower_Fan_and_Regulator_Replacement.htm

I took out the glove box as suggested. https://www.pelicanparts.com/techarticles/Porsche-Cayenne/30-BODY-Glove_Box_Catch_Replacement/30-BODY-Glove_Box_Catch_Replacement.htm
it was not too difficult.

[RNajarian]

Thanks Flintstone,

I should have listened to you in the first place. . . Guess I’m hard headed. I’m ordering the part now.

[fintstone]

You never know (still might be something else)...but if you want to be sure before you buy the part, go ahead and pull it out and test it. You are going to have to take it out anyways...and the job will be half done. You should be able to just put 12v on one pin and ground on the other and run it. Takes everything else out of the circuit (eliminates them). You might even be able to access and do that while installed.