I noticed that the sensors in the model appear to be placed incorrectly.
For through variable (flowrate, current, heat flux) sensors, it needs to be in series of the flow, i.e. the fluid flow through the block (A to B or B to A; both OK but opposite sign).
For across variable sensors, it always measures a difference, so you need a reference point or place the sensor over two different nodes to measure (pressure, voltage, temperature) differences.
Check out this example on how the sensors should be placed:
Go into the subsystem labeled "S" and look for the sensors.
