If the Air Compressor would be under Body instead of Engine, not all engine mods would be broken because of the last update. It's only a small adjustment, but it has a big impact on the mods for the Wentward DT40L
Even if you did that the air compressor still wouldn't work with all the mod engines as in order to run the compressor the engine needs to be altered to have an extra powertrain output.
my mod didn't include the slots for air systems and it broke as soon as I added the stock air compressor and tank slots everything worked good, I did get a bad revue after the update because I didn't support/know about the issue.