We have a 250 Ton York YS that just started driving the slide valve full open and not unloading when the water reaches setpoint. The control side appears to be working correctly but the valve is not.
I have watched it operate in the service mode where you can see the pulse for load and unload signals. With gages attached to both sides of the actuator you can see the pressure go up on the unload side but the valve does not move. If you go to manual and give it a constant unload signal it will drive the valve closed. Same pressure rise.
The Technician has already changed out the solenoid valve part that is attached to the top of the 4 Way directional valve sub plate.
Has anyone had this problem?