Macster

A bit of background. The 2003 Turbo has been making a non-rythmetic knocking noise -- not a very loud knocking noise which is more like a tapping noise -- when the cabin vent fan is running. The noise sounds like it is coming from low under the dash on the passenger side of the car.

The noise is not loud really only audible when the car is standing still and the engine idling.

The noise does not seem to be affected by the speed of the cabin vent fan other than if I work the fan speed control to turn the fan off the noise stops. Playing with the vent controls -- selecting say the top of the dash vent over the center and bottom dash vent outlets -- doesn't affect the noise either.

The auto climate system works fine otherwise either with the A/C compressor on or off.

Like me, the tech suspected an air flap servo was acting up or an air flap servo arm had come loose. He said the flaps/servos in the Turbo (and the Cayman which shares the same flaps?) frequently act up and require replacement both in the Cayman and the Turbo. Figures.

Anyhow I turned the car over to the tech and told him to find the source of the noise and advise me what it would take to address it. I was not willing to give him carte blanche to possibly replace the A/C unit. ($$$$)

The SM called me yesterday to say the tech believes the noise is from the cabin vent fan/blower but there are no error codes logged in the A/C system's controller and the fan/blower motor, et al, looked ok upon removal and inspection. Also, upon reinstallation the noise is no longer present.

The advice then is to just resume driving the car and if the noise comes back then it can be addressed by I guess replacing the fan/blower/motor assembly which for the Turbo is a $750 assembly. Figures.

Oh, and the ratcheting like noise that the dash emits -- more from the center of the dash and up higher -- sometimes when I get into the car and even before I start the engine is suspected of coming from the head of the CD player. The tech reported the unit has no error codes logged and the unit checks out ok -- the very rare times I use the player or the CD magazine in the front trunk they work just fine -- so he advised not doing anything at this time. The noise doesn't really bother me and I'm not wiling to fund a hunting expedition and possibly replacing an otherwise good CD unit with one that might make the same noise.

Also, the tech found the battery low. This in spite of my recently restricting the use of the Turbo and only driving the car twice a week for around 25 to 30 miles each drive to top up the battery, circulate vital fluids, etc. Also, I am careful to unplug any electrical loads like the V1 radar detector and the NAV unit when the car is parked even overnight.

Might mention that before this recent decision to use the Turbo less, the Turbo served as my daily driver when my Boxster was in the shop for 2 months with mainly a nasty air bag warning light problem. I put around 3K miles on the Turbo in those 2 months. With the return of my Boxster the Boxster now serves as my daily driver again.

The Turbo battery is not that old. The tech told me that the 996 Turbo is hard on batteries. I have in the past not believed this to be the case as it appeared the battery in my car was just fine given I used the car "regularly". But I'm coming around to believing there is something to this "the Turbo is hard on batteries" thing.

Trouble is I have no place to plug in a battery maintainer so I'll just have to live with this for now.

In the service bay, the tech connected a very nice battery charger/maintainer/reconditioner and left it connected for a few days and based on what the device reports now has resurrected the battery. The procedure I was told is the device drains the battery and then recharges it and somehow knows the battery is healthy based on the recharging telemetry.

We'll see for I pick the car up later this AM. Oh, I took it in for an oil/filter service -- due since the car's odometer reached/rolled over 135K miles a while back -- initially and that light/faint knocking/tapping noise from the dash area.

rmc1148

The heater/ac fan can be bought oem for around 500 and after market for under 300.

Macster

Thanks for that. When (if) the time comes I'll keep that in mind. I may just buy the thing and had the tech remove the old one and install the new one.

It may be something I can get at myself, too. I don't think the tech had to work very hard to get the unit out or in again. I believe he got to it from inside the cabin. I will have to check on this.

rmc1148

I was wondering myself how hard it is to remove?

Macster

You know I have a sneaking suspicion the A/C fan noise and the ratcheting/clicking noise from the CD head is related and was due to the battery being low.

More than a few times this car has manifested odd behavior that was "cured" after what proved to be a weak/going bad or just plain old bad battery was replaced.

Some time after I first bought the car every once in a while I'd turn on the key and start the engine and the radio would come on on its own and on a station not of my choosing, not even one assigned to one of the push buttons. It was like the radio was possessed. Or the radio would come on but not make a sound, act like some semi-zombie radio. All the controls worked, just no sound. The only thing that would cure it would be to turn off the engine and the ignition and let the car sit awhile. Upon restart all would be just fine.

Then the battery went flat and I had it replaced. No more symptoms for a few months but then some returned and after just 7 months the new battery was dead. This was replaced -- under battery warranty -- and again the symptoms were absent until recently.

As the tech pointed out the battery was down to about 60% on its way to being "flat" and his resurrecting the battery accounts for the fact the fan got quiet upon being reinstated. I'm sure with the fan out he would have noticed any loose bearings or a wobbly shaft, bent fan housing, some fan runout, loose fan mounting, something that could account for the noise. And the fact the noise was not regular but quite irregular just has me thinking the battery was at the bottom of this noise.

I bet the ratcheting/clicking noise from the center of the dash stays away now too.

Next time I start hearing any noises I'm going to check the battery for low charge maybe even take the car to work and with a good battery charger give it a topping up while I'm working. Or drop the car off at the dealer and have the tech do this just to see if this "cures" the noises.

rmc1148

You cant get an extension cord to your car for tender?

PCarSD

Right after I purchase my 996tt, I noticed a clicking ratcheting noise from the dash as well, usually for the first five minutes after I started the car. If I popped my head I the passenger footwell, it was louder, and I could feel a vibration when I touched the glovebox nearest the console.

I reached my hand behind the lower dash and found a servo moving the vent from cold to hot (tested by changing the cabin temp and feeling the servo move right to left). What seemed to be happening is that, upon startup, even with the fan off, the temp servo was turning as far towards cold as possible, hitting its limit, but still trying to move further towards cold (towards passenger side), hence the clicking.

I gentlely twisted the servo when it did this and the problem went away.

Macster

No. Where I live my Turbo is parked a distance away from my apartment and there are no electrical outlets at the carports. An extension cord from my place would be around 100' long and extend over one driveway and across several walkways -- where it would be a trip hazard -- and lawn areas -- where the lawn care workers would probably chop it to bits with a lawnmower.

Besides the parking area is not secure and I would be afraid the charger and extension cord would be stolen in no time. And I have no desire to leave the car exposed by having its front trunk lid open. There is the CD magazine in the front trunk along with the toolkit, jack, and inflatable spare tire.

Using a battery charger/maintainer at home is just not feasible.

rmc1148

See your dilemma Macster.

"02996ttx50

i found it nearly impossible to operate this thing without regular and consistent use of a trickle charger. i'm surprised that you haven't had more low battery related issues over the many years.

i have never had a car with such demands on the battery and the accompanying symptoms that a low battery can cause and mislead diagnosis/troubleshooting, than this one.