There are two ways to do this:
Use a compatible center console:
Try to find a center console from another car—like the Axio or Fielder—that fits the E140 and already includes rear AC vents. Once you have that, you just need to route plastic air ducts from the front of the car (under the gear shifter) to the rear vent.
3D print a custom vent:
You can 3D print a rear AC vent with a U-bend behind it, allowing you to run a 3D-printed duct or a small HVAC pipe from the dashboard to the new rear vent. This is the best option in terms of airflow and customization but requires 3D printing knowledge and possibly a 3D scanner to scan the rear ashtray and design a proper retrofit.
In both cases, you can hook the rear AC duct to the vent that blows air toward your feet. This way, you don’t need to modify the original AC ducting inside the dashboard.
Note: If you already have a 3D printer, this mod is worth trying. Otherwise, it may not be worth the effort, since the stock center AC vents in the Corolla have strong airflow and can cool the rear of the car effectively due to the cabin’s compact size.
Alternative suggestion:
A more practical and functional mod would be to add rear charging ports, an AUX connection, or 12V cigarette lighter sockets (for powering chargers, vacuum pumps, etc.). This is easier to install since it can be integrated into the existing rear ashtray housing. You just need to design a plastic insert that fits snugly into the ashtray and houses your selected ports.
