Danfoss 90 Series - Service Manual

Other manuals for Danfoss 90 Series

Installation6 pages

Questions and Answers

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brettmartinAug 13, 2025
How to fix low motor output torque on Danfoss 90 Series Water Pump?
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  Keith HarrisonAug 13, 2025
  Low motor output torque on a Danfoss Water Pump can be due to low system pressure at the motor, so measure the system pressure at the motor and increase the pressure limiter setting if it's low. It can also happen when minimum motor displacement yields low output torque, so check the control supply pressure, repair the displacement control, and check the motor control orifices. Internal leakage can also reduce system pressure, so check for leaking O-rings, gaskets, and other fittings, repairing the unit as required or replacing the leaking unit.
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Jesus Thompson MDAug 17, 2025
What causes improper motor output speed in a Danfoss 90 Series Water Pump?
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  Christopher DavisAug 17, 2025
  Improper motor output speed in a Danfoss Water Pump can arise from several issues. Insufficient hydraulic fluid will reduce motor speed, so fill the oil to the proper level. Incorrect outflow affects output speed, indicating the swashplate is out of position; measure pump output and check for proper pump speed, ensuring the pump is in full stroke. If the variable motor displacement control isn't functioning correctly, the variable motor swashplate may be in the wrong position; check if the variable motor displacement control is responding, and if not, repair or replace the control. Internal leakage can also reduce system pressure, so check for leaking O-rings, gaskets, and other fittings, repairing the unit as required or replacing the leaky unit.
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Krista FoxAug 28, 2025
Why is my Danfoss 90 Series Water Pump system making noise or vibrating?
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  Lauren FletcherAug 28, 2025
  System noise or vibration in your Danfoss Water Pump can stem from several causes. Insufficient hydraulic fluid can lead to cavitation, so fill the reservoir to the proper level. Air bubbles can also cause cavitation; look for foam in the reservoir and check for leaks on the inlet side of the system loop, then repair. High inlet vacuum can also cause noise, so inspect and replace the filter if necessary and check for proper suction line size. Additionally, a loose shaft coupling or misaligned shafts can cause excessive noise, so replace the loose shaft coupling or align the shafts.
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Amy GlennSep 1, 2025
Why is my Danfoss Water Pump transmission operating normally in one direction only?
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  Timothy FranklinSep 1, 2025
  If your Danfoss Water Pump transmission operates normally in one direction only, the input to the control module may be operating improperly; check the control input and repair or replace it as necessary. Control linkages might not be secure, or control orifices could be blocked; repair or replace the control module as necessary. Interchanging the multi-function valves can help determine if the problem is related to the valve functions; if the problem changes direction after interchanging them, repair or replace the valve on the side that does not operate. Also, if charge pressure decays in one direction, the loop flushing valve may be sticking; measure charge pressure in forward and reverse, and if pressure decays in one direction, inspect and repair the motor loop flushing valve.
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John MurphySep 5, 2025
Why is my Danfoss Water Pump system response sluggish?
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  Franklin BaileySep 5, 2025
  A sluggish system response in your Danfoss Water Pump can be caused by insufficient hydraulic fluid, so fill the reservoir to the proper level. Incorrect pressure settings can also affect system reaction time, so adjust or replace the multi-function valves. High pump inlet vacuum can reduce system pressure, so measure the charge inlet vacuum and replace the inlet filter if it's high. Low engine speed reduces system performance, so adjust the engine speed. Incorrect charge or control pressures also affect system performance, so measure and correct them if necessary. Finally, internal leakage reduces system pressure, so check for leakage in O-rings, gaskets, and other fittings.
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jennifer32Sep 8, 2025
How to deal with a Danfoss 90 Series Water Pump when neutral is difficult to find?
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  jackbernardSep 8, 2025
  If neutral is difficult or impossible to find on your Danfoss Water Pump, it could be due to the input to the control module operating improperly, so check the control input and repair or replace as necessary. Another cause could be that the control linkages are not secure, or the control orifices are blocked; adjust, repair, or replace the control module as necessary. If the multifunction valve is leaking, swap the multifunction valves; if the system changes direction, replace the defective valve.
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seth72Nov 19, 2025
Why is my Danfoss Water Pump system operating hot?
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  Tyler VazquezNov 19, 2025
  Your Danfoss Water Pump system might be operating hot due to several reasons. It could be that there is insufficient hydraulic fluid, so you should fill the reservoir to the proper level. Another cause may be that the heat exchanger isn't sufficiently cooling the system, so check the air flow and input air temperature for the heat exchanger and clean, repair, or replace it. Low charge pressure, high inlet vacuum, system relief settings that are too low, leakage, or high system pressure can also cause the system to overheat. Measure charge pressure and inspect, adjust, or replace the charge relief valve, or repair the leaky charge pump. Check charge inlet vacuum and inspect the inlet filter, replacing it if necessary. Verify the settings of pressure limiters and high-pressure relief valves,...
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Cynthia BrownNov 23, 2025
What to do if my Danfoss 90 Series Water Pump system will not operate in either direction?
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  jeffreyramirezNov 23, 2025
  If your Danfoss Water Pump system isn't operating in either direction, start by checking the hydraulic fluid level and fill the reservoir to the proper level if it's low. Inspect the control input to the control module and repair or replace as necessary. Also, verify that the control linkage is secure and the control orifices aren't blocked; repair or replace the control module if needed. Ensure the bypass valves are closed, replacing the multi-function valve if it's defective. Measure charge pressure with the pump in neutral. If the pressure is low, adjust or replace the pump charge relief valve as necessary. Inspect the filter and replace it if clogged. Repair or replace the charge pump if it's malfunctioning. Measure system pressure and repair or replace multi-function valve(s) if defec...