Latest Fault!! Volt gauge fluctuating - A/C display flashing

So the last couple of months have been a PITA regarding buying parts and fixing my 996. I'm sure a lot of this is down to it not being used as much as I used to over Winter. The first thing that happened was a failed coil pack so I bought a full set to fit along with a set of spark plugs. A major service. A strip down and rebuild of the O/S headlight as the indicator stopped working and a headlight reflector came loose. My Geo needed setting after needing a couple of new front coffin arms due to a ball joint failing its MOT. The emissions also caused problems with the MOT but I have a work around but still had to order a new vent pipe which still needs to be fitted. My drivers door mirror motor stopped working so I bought another motor to fix that. My O/S door was intermittently stopping the window dropping so I had to buy a new door latch. The car became hesitant, I think a new MAF has now cleared this. I started the car up on Monday and I got a whirring noise from the engine and after spraying a little WD-40 behind the idler pulleys it seemed these are on their way out. For this I have bought 3 new bearings to fit rather than shell out the full £70 each for the new pulleys as they went quiet after a bit of WD. So now to today, I noticed when I was idling in the car the cars A/C unit started flashing on and off in unison with the voltage gauge on the dash rising and falling. It was rising to around 15v for a split second and dropping back to its normal position :roll: Any Ideas what I now need to order, any usual reasons this would happen, I was thinking maybe voltage regulator but I've never had one go so I'm unsure of the symptoms :?:

Yep, voltage regulator on the alternator :sad: Have you got a code reader, you can see the voltage output on the one I have. I think you are right, more use on a regular basis is the key to happy motoring, my 996.1 is up for MOT in March...........1000 miles driven in the last 12 months :sad:

OK thanks, I'll be plugging into it tomorrow anyway so will be going through everything. It only did it once today but I did notice my A/C unit flashing last week but didn't notice the gauge at the time. I thought nothing else of it until today, unsure with it being intermittent that it will show up as a fault? I'll do the regulator at the same time as the idler pulley bearings I have planned to do. I did check how many miles I have done in 2018 and I was shocked that I have probably done about 8000, I thought it was a lot less but I guess most of that was in the Summer and its only getting used sporadically at the moment in this damp cold climate, even though it's kept in the garage.

Trying to catch an intermittent electrical fault is a PITA, it`s what I do for a living :lol: Depends on the scan time of your code reader/pc if will actually see it or not, hence why the mention of the Pico scope in your other thread, you would see it easily with one of those :grin: My Boxster gets most of the "fun miles", I actually did 4000 in that last year :sad: My poor old Merc has to cope with 50,000 a year........................things need to change I think, Porsche for a daily driver I think :grin:

I have run the car today for a short while and I think my display and gauge fluctuating may be connected with my driving hesitation issue shown in my other thread. The alternator regulator arrived today so I'll need to get this fitted to hopefully clear this problem. This is what is happening to my dash and I also can hear the A/C fan dropping in time with this. And yes my LCD display does need replacing but i haven't get around to doing that particular job yet. :roll:

Wow, that is running rough on tickover, overcharging too, anything over 14.4V will boil the battery in a short period of time :nooo:

Luckily its only intermittent but tonight it did it more than ever before, it does seem to coincide with the engine hesitating too?? I'll swap that regulator over ASAP and fingers crossed....

Are you going to be working on it tomorrow ? I can pop up with my code reader and whatnot as I was supposed to on Thursday :thumb:

I probably won't know until tomorrow, I had been commandeered to go out for the day and I was planning on taking the 996 but I don't want to cook the electrics now.

Yes, best not to drive it until the Voltage surge is sorted so as not to fry anything expensive. Drop me a text if you`re going to be working on it and I can pop up :thumb:

I'll let you know in the morning. :thumb:

That voltage reg is toast. Possibly diode(s) too as there's loads of fluctuation so you're probably hitting everything with AC. I wouldn't run that until fixed!

[Image-only or quote-only post; no author-written text.]

Going to swap the regulator over first thing, I hope it's just that?

I'm not sure if the diode pack is separate.. Best way to check if a diode is failed is look at the output waveform (it shouldn't really be a very bumpy waveform if the diodes are working!) from the alternator. https://www.picoauto.com/library/automotive-guided-tests/alternator-ac-ripple-diode-test/