raiderrider

Hello everyone. I purchased my 2009 A8L about 2-3 months ago and I absolutely love the car. Not more than my Challenger, just different. lol. I've read the intro sticky, and know I should pick up VCDS, but I just haven't done so yet. However, it will be in the very near future.

I was having a problem where approximately every 15-20 minutes of driving with the AC running, the air would cease being cold and go to warm, almost hot. The fan was still running and warm/hot air was blowing out of the vents, for about 5 seconds or so, then it would go back to cold. I searched here on the forum and saw that the issue might be an ambient temp sensor, just behind the bumper. I had that replaced. The AC system still does this, but it is more rare, and the air doesn't get as warm. Previously, I took the vehicle to an Audi dealer for a separate issue. Their diagnostic reveled that I needed to replace the left cooling fan motor. Could these two things be related? I used the Carista app to clear the code, but it returned.

Second issue. The trunk seems to have a mind of its own. Most of the time, when either button is pressed (inside, fob or on the trunk itself), the trunk tries to open (you can hear the motor/gears operating), and the right side will go up slightly, but the driver's side doesn't, and the trunk closes itself. Immediately press the button again, and it opens up normally. I've done some searching on this forum and have seen information related to replacing the motor, but that doesn't seem to be my problem. The motor, at least on the passenger side of the trunk, seems plenty strong enough and opens smoothly. I've tried hitting different parts with a little WD40, but maybe I haven't been thorough enough?

Finally, is there any nice person in the Washington, DC with VCDS that could run a diagnostic on my car?

Jack88

Well, I like your choice in cars, there. Your A/C problem sounds like an issue with automatic function of the climate control, like it can't figure out the temperature of the air inside the car. Just my guess, anyway, it's not something I have any experience with. As far as the trunk, it seems everyone who has had to replace the trunk motor has had one side that struggled more than the other, with it getting progressively worse until the motor just pushes up one side a little bit before it gives up.

If you have any desire to do work yourself on the car, the Rosstech cable will be required. Doing work yourself will save a lot of money, and if you have any mechanical aptitude, a lot of it is simple enough. There's a solid independent shop in Severn I have used a couple times, as well.

MiMitch

i see a solid car/bromance in the works here. and yes yes yes to the saving $$$ by working on it yourself, but.... sinister in severn has fair prices and the owner is ex audi dealership lead tech.

mishar

Welcome to the board!

Your AC probably needs more gas. Trunk has only one motor and it is on the right side. That's why that side goes up first. Since it is 2009 it is already new motor, so it is probably clutch. Some cleaning and degreasing should help.

MiMitch

i have jack88s cable in michigan
i have a couple things to do with it yet, but im sure i can send it back down rather soon, may be able to hook up with him. (he's not very nice though )

Hennessy

I've got VCDS I bought a couple years ago and still havent' used yet cause I wasn't around enough. Ironically enough I was planning on installing and doing a scan on my car this weekend. PM me if you want to try one day this weekend I stay in close?

MP4.2+6.0

Hi & welcome.

There is only one trunk motor, on the U.S. passenger side above the battery area. Sounds like maybe a hinge is bent or you need to lubricate them more. You can also replace the little gas struts, which might be tired.

A/C--can't be sure, but if Audi dealer said a fan was bad I would defer to their diagnostic work. If a fan isn't coming on, it won't pass air over the exterior A/C panel in front of the radiator sufficiently, at least around town. There are a series of basic old school automotive diagnostics that come in here too--some of what the sticky gets at. An informal test for this could be if A/C works on the open road in general, but not in traffic, then indeed a fan (or its controller) could be the issue. Another thing to look for is if you don't hear much fan noise a lot of the time for ordinary cooling, but when it comes on it is suddenly at "jet engine" speed and noise. If it does that, it has lost its low fan operating capability, which is what is the way it normally runs much of the time. Said alternately or as yet another way to check, even with car at first cold start of the day in even moderate weather, if you have the A/C on, a fan should be spinning at some speed, while with A/C switched off at cold start the fans will be off until motor (coolant) heats up. If they are just plain off when A/C is on and car first (cold) started, you basically then conclude you have a definite fan issue. And yes, get VCDS for real diagnostic capability. It will pay for itself almost right away, for example chasing down this A/C issue.

If not that fan diagnosis as far as other ideas, I might suspect the A/C refrigerant charge, more so if it is reluctant to cool down early on, and especially if it gets progressively worse over some months. Or alternately, if happening more only on longer drives, then the inside A/C panel may be freezing up, perhaps due to blocked drains.

raiderrider

Thanks for all of the great responses everyone.
Jack88
- I do intend to do some work myself; however, I would really like to be knowledgable about whatever issues I may have before going to have the vehicle serviced, so the VCDS is very high on my list. That way, I'm really familiar with a problem (and will problem bring it up on this board) and potential solutions. And, yes we both have chosen vehicles amazingly well.

MiMitch
- I think will check out Sinister the next time I need service or problem solving. Looks like a great shop, with great ownership. Let me know when you're done with the cable, and if Jack88 doesn't mind, and I still don't have one by then, I would love to borrow it.

Mishar
- You say the AC may need more "gas." Are you referring to freon? I will re-examine the trunk and grease the hell out of the moving parts, struts, etc.

Hennessy
- The only day I'm around this weekend will be Monday. I'm off and will probably fire up the smoke to make some ribs, pulled pork or something like that. Riding my motorcycle up to Cleveland tomorrow. Back Sunday. The following weekend might be a good option.

MP4.2
- The Audi dealer also said I might have trouble if around town, in stop and go traffic; However, I've been in plenty of HOT stop and go traffic around DC since June. Many days in the high 90s. AC system and the fan did not seem to perform any differently or unusually. I do hear the fan for ordinary cooling and it is not at supersonic speed unless appropriate (for example, I've turned the temp way down under 70, hot weather, and the car hasn't warmed up yet). Other than the momentary hot air, the system seems to peform normally, i.e. fan will come on at first cold start of the day if the AC is on, but will not if the AC is switched off at cold start. This is why I didn't get the fan replaced immediately when the dealer told me about it. Just didn't seem that it was a problem, so I wanted to wait to see if I had any further problems, which I haven't.

MP4.2+6.0

FWIW, my experience is the fan NEVER goes to jet engine mode unless 1. there is a cooling system fault code and it had kicked into its safe backup mode (like a bad coolant temp. sensor), 2. it is super hot (endless running in stop and go traffic) or you force it by extreme running/revving for a long time (like 20 minutes +), 3. there is something wrong with the variable speed fan set up. NO setting of the A/C temp should do it by itself absent a hot motor. Do you physically see and hear a fan running softly at idle after cold start w/ AC on? If not, it is gone. If normal, then the refrigerant--or as Misha called it, the gas. Freon was the old stuff, though still the vernacular. My 2006 needed a charge a couple summers ago (it was down to less than half), as did another couple of S8s I recall that were at least 2007's. The system holds very little refrigerant due to enviro regs (only about 600g, way down from old freon days), so modest losses can leave it way down % wise.

TSHong

As previous posts have stated, I would make sure that you have the right amount of refrigerant in the system. This can only really be done accurately by vacuuming out the system and putting back the specified amount back in. Then move on to some other diagnostics on the A/C.

As for the trunk, the 09 should have the updated motor and hinges but I would say your right hinge is slightly bent.