Mcquay Hsa Screw Compressor Service Manual
Introduction
- Strip and inspect rotor assembly, bearings, seals, and replace worn parts.
| Problem | Likely Cause (from manual) | Solution | | :--- | :--- | :--- | | High discharge temp | Low suction superheat or oil starvation | Check expansion valve, clean oil strainer | | No capacity control | Slide valve stuck or broken piston ring | Remove actuator, inspect slide valve bore | | Loud rattling noise | Worn rotor bearings or debris in rotors | Immediate teardown – do not restart | | Oil level dropping | Failed oil separator coalescer or leaking shaft seal | Replace separator element, replace shaft seal kit |
- Actuator may be hydraulic or stepper motor.
- Verify slide valve position sensor (0–5 VDC or 4–20 mA).
- Manual override: remove actuator and rotate slide valve stem with wrench.
