This section provides troubleshooting steps to follow if you are having problems with your machine until
you solve the problem. Some of the troubleshooting items are system specific. Always observe the safety
precautions listed in the Introduction section and precautions related to your specific equipment.
High Inlet Vacuum
High inlet vacuum causes cavitation which can damage internal pump components.
Unintended Machine Movement
Unintended movement of the machine or mechanism may cause injury to the technician or bystanders.
Secure the machine or disable/disconnect the mechanism while servicing to protect against unintended
movement.
Fluid Under Pressure
Escaping hydraulic fluid under pressure can have sufficient force to penetrate your skin causing serious
injury and/or infection. This fluid may also be hot enough to cause burns.
Relieve pressure in the system before removing hoses, fittings, gauges, or components. Never use your
hand or any other body part to check for leaks in a pressurized line. Use caution when dealing with
hydraulic fluid under pressure. Seek medical attention immediately if you are cut by hydraulic fluid.
Hazardous Material
Hydraulic fluid contains hazardous material.
Avoid prolonged contact with hydraulic fluid. Always dispose of used hydraulic fluid according to state,
and federal environmental regulations.
Electrical Troubleshooting
Electrical troubleshooting
Item Description Action
Control operates pump in
one direction only.
Control coil failure
•
Measure resistance at coil pins. Resistance should be
14.20 Ω (24V) or 3.66 Ω (12V) at 20°C [70°F].
•
Replace coil.
No pump function No power to controller Restore power to controller.
Erratic pump function Electrical connection to pump is bad. Disconnect connection, check wires, reconnect wires.
Filter bypass indicator switch Filter switch may be bad.
•
Check/replace filter switch.
•
Add gauge to filter bypass port to verify proper fluid flow
and verify switch operation by measuring resistance.
‒
Open resistance ≥ 510 Ω
‒
Closed resistance ≤ 122 Ω
Use a manual override to check proper pump operation and verify electrical problem, if available.
Integral Filter Bypass
Item Description Action
Filter bypass activated Filter is plugged causing fluid to bypass filter. Replace filter. Check that bypass switch indicates proper
operation after filter is replaced.
Filter bypass indicator switch Filter bypass indicator switch is indicating wrong bypass
situation.
Check/replace filter switch.
•
Open resistance ≥ 510 Ω
•
Closed resistance ≤ 122 Ω
Service Manual
H1P 069—H1P 250 Axial Piston Single Pumps
Troubleshooting
30 |
©
Danfoss | September 2020 AX152886482551en-000504
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