Had a look at the cap fitted to the air comp I was looking at.

Its capacitor is slightly different, a 40uf 262/CR404U. Some of the label has rubbed away, but it has the insertion time as "Autotarabile".
Measuring the resistance both ways just gave the usual charging as on a normal cap, quickly going from 0 to OL.
Wired it to live and neutral on its own, and it ramped its current up to 3A and sat there. Didnt leave it powered up to long, maybe 3-4 seconds.

Measured the resistance between the motors leads.

B - W = 3.4 Ohms
B - R going to 40uf cap = 1.1 Ohms
B - R going to neutral = 1.1 Ohms
R - R = 0.0 Ohms
R going to 40uf cap - W = 4.5 Ohms
R going to neutral - W = 4.5 Ohms

Kinda looks like its just a CSCR motor with a funny start cap.

Cheers