Thank you, BlackSVT.

The A/C is working beautifully. Everything is, except the recalcitrant stop-start.

The fan blows cold air instantaneously, without obstructions. There is no indication of the expansion valve not working and that the A/C evaporator coils have iced.

[As a side note, BlackSVT, I would have Audi check the expansion valve on your Q5 as a malfunctioning one will freeze your evaporator coils, exactly as you describe.]

I will try your suggestion as a test (which makes the stop-start practically useless to me). I also wondered why you want cabin-air recirculation turned off since that decreases the load on the compressor and, thus, the electrical system with the engine stopped.

Either way, come Monday 22 I will drop the lovely for diagnostic code checks to the Audi dealer. At best, they will be authoritative on which user-settlable thresholds will cancel auto stop-start. And, at worst, I will get the Q5 washed and detailed for free.

Thanks BalckSVT. Will post my findings next week.

I also freeze my cabin and turn on the heated seats to help warm my back before cycling or golfing. I haven't tried using the heated seat and ventilated seat at the same time but now I am going to...

The "start/stop" function is of no use to me at all. I find it stilly and the opposite of why I want a peppy car.

Apparently from what you just said, you may have the package I do not: perforated, ventilated seats. I went for the sport package instead, which provides better back support and paddle shifters. So, when I heat my backrest, my use case does not have air blown through the seat at the same time.

I feel that the "stop-start" system proves its value for city driving, as long a it does not hesitate/stop when moving from rest, potentially being reared by a trailing car. So this is an option that better be flawless in operation 100% of time.

One final note: Above all, I dislike being hot. My body really yearns for a Pacific Northwest weather. I do not consider 68 degrees freezing -- not even close. I keep the thermostat on my home at 65 degrees and love cold air, so I hate Washington DC summer weather.

If stop-start does not work under my loads, as I describe above, then it simply will never going to work for me.

More later when I find out. Thanks!

I was able to have my start-stop engage some yesterday evening coming home with 90F outside temp, A/C set to 68, and seat heaters on. I left my fan speed on auto, though, so the fan was able to ramp down from 8 while driving to 4 when start-stop engaged. Might be possible that if you specifically set a high fan speed then instead of overriding your requested fan speed it'll just not engage start-stop if it'll be too much electrical load.

You might try setting fan speed to auto and let the car manage the exact speed and see if that lets the start-stop engage. Whether you're okay with the slower fan speed while stopped is entirely another matter, and if it doesn't work then it's not so much a problem with the start-stop system as it just not being able to support the workload you need. Could always just hit the button to deactivate the system entirely so it doesn't even waste its time checking to see that it won't (most likely) be able to engage in that case. Or maybe auto fan speed lets it engage and you're still happy with the comfort level and that start-stop is able to activate.

I think the stop/start system will always have issues when the aircon is set to cooler than the outside temperature, at least mine does. I like a cool car myself even when the outside temp is fairly low (I just like the feeling of cool air on my face and hands) and I see that the S/S system doesn't like it if I have too low a temp. Today with a warmed car and outside temp of 50f I put a/c to 68f (warming the cabin) on fan speed 3 and the S/S worked perfectly. In the summer I remember having 85-90f outside and my a/c on LOW with a fan of about 5 and there was no way the S/S would work.

PS I have used the heated seats on my ventilated comfort seats and have to turn them off after 3 minutes so I dont burn my a55!!

Start/stop works, but A/C comfort suffers in the summer sun, it is not pleasant. I will deactivate start/stop under those circumstances so to get constant A/C.

In the depth of winter, start/stop hardly works.

Other than those times, it works great.

I guess so, I have a TDI with Tech, Luxury, S-line, Tow, B&O and Sport Interior packages( I guess the same seats you have with the paddle shifters). It seems the ventilated seats are part of the Luxury package.

IDale, that is probably the most lucid explanation of why the stop-start auto-cancels on my Q5. It makes perfect sense.

But I will not be able to test your hypothesis until this weekend, as I have parked the Q5 underground while my wife is away visiting family. I am only allowed to drive her Q5 on weekends. LOL!

Even if you hypothesis proves correct, I have decided to drop the Q5 for diagnostic stop-start service at my Audi dealer. And let them report back on those stop-start thresholds. At least I will get a nice car wash out of it.

But your hypothesis makes the most sense, as it provides the engine management system a degree of freedom my settings to not allow.

Thanks!

As was noted earlier, this is likely the reason why your start-stop does not engage. Even after only a short Starbucks break, when you return to the car, the interior temp has already increased, and AC has to work harder to bring the temperature down again, and until it does, start-stop will not work.

As iDale hypothesized, not leaving some degree of freedom to the stop-start (e.g. forcing the setting of a low temperature with high fan speed like I did) will probably auto-cancel. Setting the cabin temperature to LO, as you described, is probably a non-starter either. On winter-time anytime you turn-on the window defroster the stop-start is SOOLed. i hope to get these thresholds authoritatively after Monday.

Have no idea how the ventilated comfort seats work and how well they wear. Never seen them in stock over here, and on Premium Plus, you either go for standard seats, sport seats, or perforated seats -- all mutually exclusive.