Totally depends. If you have to stop and start a lot, it can decrease range, however if you can keep a steady, but slow, speed it can improve range. A/C doesn't matter much, heater does.
Actually, this is partially true. In low temperatures the car will work more to achieve the goal so that will increase the HVAC consumption in the long run, but the A/C does pull a lot of juice too, not just heater.
You can easily test it yourself as I did in this video. Plug in the charging cable, turn off charging and check the consumption of the HVAC. It goes over 4kW even though the temperatures were mild/warm 22C.
https://www.youtube.com/watch?v=wE5QPjUdHGY
The problem with this thread is that there are a lot of variables - there is stop and go traffic and there is stop and go traffic. There is warm weather and warm weather. So everybody is reporting things, but nobody is reporting the whole picture:
You also don't know how long the car has been driving before that and how the HVAC was preconditioned.
General speaking - the faster you go, the more drag. But since you will travel more distance for shorter time, the HVAC consumption will be lower relative to the distance (4kW in 1 hour is 4kWh. 4kW in 30 minutes is just 2kWh consumed. If you travel the same distance for 10 mintues instead of 1 hour your consumption will still be lower)
HVAC and wind resistance play a very, very big role in EVs actually and especially on a Model 3 (S and X are way better) without a heat pump and a very, very inefficient HVAC which can pull anywhere between 1kW (low end) to 6kW on the high end.
Now depending on the stop and go and the outside temperature and how preconditioned the car was or how long you were driving before that, if the car pulls 6kW on a stop and go that takes 30 minutes, the HVAC alone will consume 3kWh.
So it is hard to tell.
But as a rule of thumbg, if you turn off HVAC (just use the passive cooling/heating without pressing "A/C") in a stop and go traffic you will barely consume anything. And if the HVAC is somewhat at steady temperature already, it will also not affect the range much.