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Check coolant flow at nozzles

With machine in EMERGENCY STOP, visually inspect all coolant nozzles for visible blockages or reduced flow patterns.

Ensure machine is locked out before inspecting coolant system

Clear nozzle blockages

Remove and clean individual nozzles using compressed air and coolant-compatible solvent. Check internal passages for chip buildup.

Use a small wire or nozzle cleaning kit to clear stubborn blockages

Inspect distribution manifold

Remove manifold cover and check for accumulated debris in main distribution channels. Clean thoroughly before reassembly.

Test system pressure

Restart coolant system and monitor pressure reading in CURRENT COMMANDS display. Verify pressure stays below Parameter 141 setting.

Locate pressure relief valve

Find the pressure relief valve on the coolant pump assembly, typically mounted on the discharge side with adjustment screw.

Relief valve is usually a small cylindrical component with a spring-loaded mechanism

Test relief valve operation

With system running, gradually increase pressure by partially blocking discharge. Relief valve should open at rated pressure (typically 50-100 PSI).

Clean or replace relief valve

If valve doesn't open, remove and clean internal components. Replace spring and seat if worn. Adjust opening pressure per manufacturer specifications.

Verify Parameter 141 setting

Access SETTING > PARAMETERS and confirm Parameter 141 (COOLANT PRESSURE LIMIT) is set appropriately for your relief valve rating.

Check pump speed parameter

Navigate to SETTING > PARAMETERS and verify Parameter 140 (COOLANT PUMP SPEED) is within manufacturer recommended range (typically 60-80%).

Lower pump speed reduces pressure but may affect coolant flow effectiveness

Monitor pump operation

Observe pump for unusual vibration, noise, or erratic pressure readings that indicate internal wear or cavitation issues.

Inspect pump discharge line

Check for restrictions in the main discharge line between pump and distribution manifold that could cause back-pressure.

Test with reduced pump speed

Temporarily reduce Parameter 140 by 10-15% and test if alarm clears while maintaining adequate coolant flow.

Access pressure sensor diagnostics

Navigate to CURRENT COMMANDS > COOLANT and observe real-time pressure reading. Compare to mechanical gauge if available.

Pressure reading should correlate with actual system pressure and pump operation

Inspect sensor connections

Check pressure sensor electrical connections for corrosion, loose terminals, or damaged wiring. Clean connections with electrical contact cleaner.

Test sensor calibration

With system off, sensor should read near zero. With system running normally, reading should be stable and reasonable for your setup.

Replace pressure sensor if faulty

If sensor readings are erratic or obviously incorrect, replace pressure sensor and recalibrate system per Haas service manual procedures.

Check coolant tank level

Verify coolant level is above minimum mark on tank sight gauge. Low level causes pump to draw air, creating pressure instability.

Inspect tank pickup tube

Ensure pickup tube is fully submerged and not cracked or loose, which would allow air ingestion into pump suction.

Add coolant and test

Fill tank to proper level with appropriate coolant mixture and run system to verify stable pressure operation without alarm.