If the "19 Amps" is labeled as the "minimum circuit ampacity" or words to that effect. Grab a hold of your hat. You could use #14. (per 310.16, 60 degree column). There was a question on the inspectors test about a 1hp motor on a 120v circuit where the right answer was "40a breaker, 14 ga wire". Strange sounding things happen around motors and HVAC units. The exception is in 240.4(G) (2008 code or in 240.4(D)ex in earlier versions).
