Troubleshooting for low coolant flow

Diagnostic codes 540 and 542

The low coolant flow diagnostic codes (540 and 542) can occur because of a low coolant level, blockages or damage in the coolant hoses, or problems with the coolant pump.

Symptoms

Code Symptoms XPR® models XPR action Code cancels with...
540 For a minimum of 40 seconds after the coolant pump is set to ON, the coolant flow rate is less than 1.9 L/min (0.5 gal/min). All models Shut down Remote on-off
542

XPR170® and XPR300®: For a minimum of 1 second, the coolant flow rate is less than 3.79 L/min (1 gal/min).

XPR460®: The low coolant flow rate limit is less than 2.5 L/min (0.66 gal/min) when the coolant temperature is ≤0°C (≤32°F) or less than 4.9 L/min (1.3 gal/min) when the coolant temperature is ≥40°C (104°F). For flow rates and temperatures that are between these values, use the same scale to calculate the limits. For example, a flow rate less than 3.8 L/min (1.0 gal/min) with a coolant temperature of ≥20°C (68°F) can also cause a 542 code to occur.

Corrective action

  1. Make sure that the coolant level in the coolant reservoir is sufficient.

    You can see the coolant level from the fill port inlet on the top of the plasma power supply. You also can see coolant levels on the Computer Numerical Control (CNC) screen or the XPR web interface.

  2. If the coolant reservoir is not full, fill it with coolant.
  3. If the coolant reservoir level is sufficient, but the code continues:
    1. Make sure that the coolant pump is ON and the gauge is spinning.
    2. Make sure that the bypass is working.
    3. Examine the coolant hoses for restrictions or blockages.
    4. Make sure that the consumables are correct for the operator-selected process.
    5. Examine the coolant filter, and replace the filter if necessary.

      Refer to Remove old coolant from the plasma cutting system.

    6. Clean the coolant pump screen, or replace the screen if you find damage.
  4. If coolant filter or coolant pump screen replacement is not necessary, do a coolant flow test to identify the source of a coolant leak or obstruction.
  5. Send a process command to start the coolant pump.

    The coolant pump starts automatically when it receives a process command.

  6. If the coolant flow test value is equal to or greater than the permitted limit, but the XPR web interface shows a lower value, examine the control Printed Circuit Board (PCB) (PCB 1 in the plasma power supply) for +15 VDC on J8 pin 1 and pin 2.
    If you get this condition...Do these steps...
    There is no voltage on J8 pin 1 and pin 2.
    1. Examine the wire harness that connects to J8.
    2. Look for a short.
    3. If no short is found, replace the control PCB.
    The voltage on J8 pin 1 and pin 2 is +15 VDC.
    1. Examine the flow sensor output (in frequency) at the control PCB.
    2. Measure the frequency on J8 pin 3 (pulse) and pin 2 (ground).
    3. If the value is different by more than 0.8 L/min (0.2 gal/min), or if there are no pulses (0 Hz), replace the flow sensor.
    Minimum flow rate limits Frequency (Hz)
    Liters per minute (L/min) U.S. gallons per minute (gal/min)
    1.89 L/min 0.5 gal/min 15 Hz
    3.78 L/min 1.0 gal/min 34 Hz
    5.67 L/min 1.5 gal/min 54 Hz
  7. If you cannot find or correct the problem, speak to your cutting machine supplier or regional Hypertherm® Technical Service team.