This may not be your problem, but you may want to check the aerator screens (unscrew from faucet end). My kitchen sink faucet would not flow water upon dewinterizing, and I found debris in aerator keeping it from flowing. Also check the in-line water filter at your water pump. BTW: I suggest you kick up the air pressure to ~30 PSI (or use your water pressure regulator connected in-line of the air hose) as 15 PSI seems pretty anemic for this task.
COL, USA, Retired