The capacity transmitter (potentiometer) provides feedback to the controller. If readings are erratic, verify the mechanical linkage is tight and recalibrate the resistance values at 0% (fully unloaded) and 100% (fully loaded) positions via the micro-tech controller interface. 6. Troubleshooting Common Diagnostic Codes Symptom / Fault Code Potential Cause Corrective Action High Discharge Temperature
By following the guidelines and recommendations outlined in the McQuay HSA screw compressor service manual, technicians and maintenance personnel can:
Clogged oil filter; faulty oil pump (if equipped); refrigerant dilution in oil.
Verify the slide valve position indicator outputs the correct resistance values (typically 0-1000 ohms) to the micro-controller panel. 6. Shaft Seal Replacement Procedures
Ensure the internal pressure of the compressor is at 0 PSI before loosening any bolts, service valves, or access plates. mcquay hsa screw compressor service manual
Before any service, it is critical to follow the safety guidelines in the manual.
Inspect the compressor shaft for scoring, burrs, or pitting. Polish lightly if needed.
Working on commercial HVAC equipment is hazardous. Adhere to these safety rules at all times:
Install the new OEM filter element and replace the O-ring seal on the cover plate. Troubleshooting Common Diagnostic Codes Symptom / Fault Code
Connect a hose to the oil drain valve at the lowest point of the compressor or oil separator.
Test motor winding insulation resistance at 500VDC or 1000VDC. Record readings to track insulation degradation over time. 4. Step-by-Step Troubleshooting Matrix
McQuay HSA screw compressors are the workhorses of industrial and commercial refrigeration and air conditioning systems. Known for their high efficiency and rugged reliability, these semi-hermetic twin-screw compressors require precise technical care to maintain peak performance.
Typically ranges from 100% down to 25% (or 10% on variable frequency drive models). or access plates. Before any service
To protect the motor stator and manage oil flow, the unit typically limits starts to no more than 6 per hour Safety Devices
Cylinder pressure = Discharge pressure + spring pressure = slide stays in same position. = + = All Seasons ° CLIMATE COMFORT Name: YouTube·HVAC Tech Guide by sreejith McQuay screw compressor NRV how To open
: Includes a suction strainer and a built-in oil filter to protect internal components. Gate-Rotors