Quote Originally Posted by erice1984 View Post
Would it be bad to PWM, basically control pressure on a water pump? given it is supposed to run constantly at 150psi?
or would you control the current into it to control the pressure?
I'm guessing some sort of A/C motor/pump assembly. Sounds to me like throwing PWM at any kind of motor not designed for it would be awful hard on it, especially an A/C motor, 'cause basically, they don't usually really work that way.

If I had to go that route, I'd use some sort of pressure vessel with a regulator on the output, like a well pump for a house might have.
Regulator set at 150psi, run the pump until you get 180psi (or whatever), turn off the pump, wait until the pressure dropped to 151psi (or whatever), turn the pump on, wash, lather, rinse, repeat... The pressure vessel maintains the output.
But...in reality, it really sounds to me like something that would just be a heck of a lot easier and probably a lot cheaper to buy off the shelf at your local hardware store. And 150psi sounds like a LOT of water pressure. My house water pressure only runs 65psi, and I've got the pressure cranked up on it.