https://www.droking.com/motor-controller/15w-brushless-motor-driver-dc-5-12v-1.5a-three-phase-brushless-sensored-controller-bldc-speed-control-switch-for-motor-hard-etc
You might have to remove the potentiometer and rig up an equivalent circuit through the pressure switch, don't know
EDIT : sorry I did not see the 15 amp load of the OP, not sure what voltage. Anyway I dont think this will work but it gives you what to search for.