Parker Air Preparation Products | FRLs | Proportional Regulator Troubleshooting

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Possible Reasons


Display will not light up.  No 24 volts power supply. Check if the wiring is connected according to the schematic wiring diagram.
Unit will not correctly respond to given setpoint.

 Wrong current applied (i.e. volts instead of mA, or mA instead of volts).




Setpoint signal is not stable enough.

Change setpoint current or re-configure the setpoint current through the software by changing parameter 4.

Check wiring if the setpoint signal lead is connected to the right pin within M12 connector (should be pin 2).

Stabilize setpoint signal input.

Display shows NoP.

Unit detects that required output pressure is higher than the supplied pressure.






No inlet pressure at all.

Adjust the inlet pressure to a higher value, preferably 0.5 bar higher than requested outlet pressure.

Give lower setpoint value which corresponds to an outpet pressure lower than the inlet pressure.


Connect port 1 to the supply pressure.

Unit behavior is not considered normal. Faulty settings made in the parameters. Reset the unit to factory settings by using the green key function under parameter 0.
Desired pressure cannot be reached.

Setpoint value too low.


Pre-set pressure limit has been changed to a lower max. outlet pressure.


Supply pressure is too low.

Increase setpoint value.


Change max. outlet pressure back to required pressure by changing parameter 19.


Increase supply pressure.

Secondary side stays pressurized.

Setpoint value is higher than 0.1 volt.


Preset pressure has been enabled to a certain pressure.

Lower your setpoint value, preferably to 0 volts.


Reset parameter 18 to 0.

Display shows unrealistic value. Display may be configured in the wrong value (bar instead of psi). Check through parameter 14 if the display is set on either psi or bar - if necessary, change it to the required setting.
Unit response time too slow or quick. Volume behind the unit is either too big or too small. Adjust the regulating speed of the unit through parameter 20.
Unit gives too much overshoot. Relation between the volume and response time is out of balance Adjust response time to a higher value through parameter 20 to achieve more accurate behavior
Unit is adjusting/regulating constantly.

Air leakage in the system behind unit.


Constant changing volume behind unit.




"Deadband" area is set too small.

Resolve leakage.


Unit needs to regulate to keep required pressure at the same level.

Try to minimize the volume changes.


Enlarge deadband setting through parameter 13 in the software (parameter 20 has to be set to 0 before changing parameter 13).

Can't enter software through touchpad.

Unit is currently working/processing.



Activating time is too short.

Make sure that the unit is in steady state while activating the software.


Hold the accept button for at least 3 seconds.

Display indicates "OL."

Wiring not according to diagram (24 volt connected on the setpoint connection pin).

Wrong setpoint value given in relation to programmed setpoint value acceptance.

Rewire so that the setpoint connection will be either 0-10v or 4-20mA.

Change over setpoint value to either V or mA, or reprogram the unit to the correct setpoint value with parameter 4.

Any other problem. Please consult factory.  

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