I may not be the best resource since our unit is new and we have not had a chance to test it out in hot weather yet, however, I did some homework before buying our 3011 and hopefully that will pay off when we do have a chance to use it.
That being said, depending on what year your unit is, how's it configured and which part of the vehicle gets hotter, there may be some things that you can do to mitigate the issue. For instance,
- The larger AC unit would help, but that is not likely going to be on your list of things to fix at this point.
- Next might be to cut down on thermal penetration. For example, our unit came without the window above the bed and room darkening shades all around. And since the thermostat is in the bedroom where it should be cooler (less window area and leakage due to smaller slide) that must be taken into account when trying to adjust temp in the rest of the unit.
- During the walk through I noticed that the vents in the bedroom (end of line) where not getting a lot of air. Closing down some vents (especially in from the bathroom) helped fix that.
- If you don't leave the air on all the time and only turn on when you need it, open the vent underneath the AC unit as opposed to using ducted vents. This should cool down the overall unit much quicker due to less restrictive airflow. Once the unit is cooler, then switch back to the ducted vents to manage the cooling better.
Then of course there are the obvious points;
- Park in the shade if you can.
- Leave AC on all the time.
- Minimize going in and out of the unit.
- Block off as much sunlight entering vehicle as possible.
- make sure AC is functioning properly