996 4S problems after dead battery

Long story short, my car was having some work done at a detail shop and was going to be there for 4-6 weeks. I stressed the importance of not draining the battery and having it hooked up to a tender. Was told no problem. Well a few weeks pass and of course I get a call stating someone disconnected the tender and the battery is completely dead. I had the battery replaced, but have been dealing with countless issues since. These include: - Air conditioning stopped working - Oil level indicator failure light at startup - When unlocking the car with the key fob button there are 2 quick horn beeps. It did not do this before, and in my experience with other brands this usually occurs when locking rather than unlocking. - The door lock button to the right of the radio stays illuminated. It remains illuminated even after pressing it. - The horn does not work when pressed. Although it still beeps when unlocking the car, and also if I push the illuminated door lock button while driving. - The windows began not lowering enough during opening and closing of doors causing the top of the window to catch the door trim. My local Porsche shop charged my AC, and replaced window regulators to start. The AC worked for about 20 minutes after the charge and then stopped. The compressor has always kicked on, just no cold air. I sent it back and was told they put dye in the system and can see a leak from the AC condenser unit. Had that replaced and the same result. Worked for about 15-20 minutes then nothing. As far as the regulators go, the driver's side is better. Passenger side was better for a day or two then completely stopped working all together and now I can't even open the door. I'm getting frustrated as I've been told each time the repairs will fix the problem. I'm starting to lean towards something quirky going on as I have read of 996's having issues after a dead battery. All of these issues popped up at once following the dead battery. Wondering if anyone has any advice or has gone through something similar. Thanks for taking the time to read this and any input is appreciated. Best, Evan

A professional shop will not just recharge or top up an A/C system, they first will (and must by law) find where it's leaking from. A good professional shop will put the system under operating pressure with nitrogen and check whether it holds pressure for an hour or so before replacing the nitrogen with R134a. Since there's now dye in the system it should be easy for them to find the leak. Sounds like you need a new passenger door lock as the microswitches in it are FUBAR and no longer detect when the inner or outer door handle is pulled upon which the window is normally dropped to clear the seal. Were the side window upper and lower limits retaught after replacement of the window mechanisms? Might help to do so (although I can't tell you how it's done exactly) Car horn and alarm beep/horn are 2 (3 actually, low and high tone for horn, just 1 for alarm/central locking) separate items. Read up on what 1 and 2 beeps mean but I seem to remember itt indicates that 1 or 2 respectively locks are being ide�tified as not having engaged. A bad/not working microswitch inside any lock can cause this too, however and are typically the cause for the beeps when all locks have engaged properly. The beeps and door lock switch remaining lit are probably linked together but I'm not sure on that one. It could be worthwhile to open the frunk, use a screwdriver to lock the latch mechanically, then disconnect the negative/ground cable from the battery terminal and charge the battery fully. Reconnect after the charge and see if you notice an improvement. If not, have all codes cleared and try again. Otoh I could imagine that all the unwanted behaviour is not caused by the first battery going completely flat.

4 to 6 weeks for a detail? Must have been one hell of a detail... I don't think all those problems started from a dead/replaced battery.. I have replaced countless batteries on 996's and never seen that.. I think some of those were already there, like the horn not working. How often did you use the horn? The Alarm horn and the two-tone horns are three separate parts located in two different locations..( alarm horn is located under the cowling for the windshield and the high/low horns are located behind the front bumper...) Sounds like there could be an issue with the alarm control though, possibly from sitting outside for so long with a water drain stopped up and wet the carpets and alarm control under the seat.... Check the rear carpet behind the drivers seat for dampness underneath on the padding...

Thanks for the replies. @hardtailer They did test with nitrogen under pressure for an hour. Apologies for my laziness in describing the "a/c recharge." I was leaning toward addressing the passenger door lock microswitch next. The upper and lower limits were retaught after replacing the regulators. I will spend some time reading up on the lock beeps. From what you've said I can see that being a result of another fault in the system. @Porschetech3 The horn always worked prior. It will actually work sporadically still but has not been working for at least the last few drives. I'm not positive, but I believe there were a few times when the car would not beep upon unlocking, the door lock button light would not be illuminated, and in turn the horn would be functional. I did have all of the drains cleaned recently. I am going to give a look at the alarm control mentioned under the seat. Thank you for this input.

scan for codes with a Durametric or PIWIS if you are able to locate one. Sounds like water got in somewhere to me.

Just a shot in the dark, but have you checked the ground connections, especially to the battery, and maybe fuses? If they were messaging with the battery, or the jump point in the fuse box, perhaps something is loose. Also, did you get a new battery, or just recharge? Is it holding voltage? Low voltage can also cause strange behaviors.