What causes Haas alarm 29?

Coolant tank level too low exposing pump inlet causing cavitation or tripping the low level float switch monitored by IOCON. Coolant pump motor thermal overload tripped due to locked rotor from debris, failed bearings, or electrical overload condition. Clogged coolant lines, nozzles, or pump inlet strainer restricting flow below the threshold required to close the coolant flow switch. Failed coolant flow switch or low level switch providing incorrect open circuit signal to IOCON even when coolant system is functioning properly. Blown fuse or open circuit breaker on coolant pump motor circuit preventing pump from starting when commanded by IOCON relay.

How do I fix Haas alarm 29?

1. Step 1: Visually inspect coolant tank level and refill to proper level, then press RESET and verify pump starts and coolant flows from programmable coolant nozzle 2. Step 2: Access Diagnostics Outputs page and manually toggle coolant pump relay while observing pump motor for starting, humming, or no response 3. Step 3: Check coolant pump motor thermal overload reset button on motor or electrical cabinet and press to reset if tripped, investigate cause of overload 4. Step 4: Remove and clean coolant pump inlet strainer and flush all coolant lines to nozzles to eliminate flow restrictions, verify adequate flow at nozzles 5. Step 5: Access Diagnostics Inputs page and monitor coolant level switch and flow switch states, manually actuate switches to verify they change state and IOCON sees the input 6. Step 6: Verify coolant pump motor supply voltage at motor terminals when output is commanded, check fuses and contactors in coolant circuit and replace failed electrical components or pump motor if needed

Haas codes

axismd.ai

Haas Controller

Overtravel/Limit · Basic · 0.5-1.5 hours

Alarm 29

Overtravel Negative B

Haas Alarm 29 fires when the coolant system monitoring detects insufficient flow, pressure, or level conditions that could damage the spindle or tooling. The NGC control monitors coolant flow through pressure switches and level sensors, triggering this alarm to prevent dry machining operations.

HaasOvertravel/LimitBasic0.5-1.5 hours

29

Overtravel Negative B

Coolant System Fault

This alarm is generated when the IOCON board detects a fault condition in the coolant system including low coolant level, failed pump motor, or coolant flow switch not detecting adequate flow. The machine monitors coolant system health to prevent running dry which can damage the coolant pump and to ensure proper cutting conditions are maintained. Automatic cycle start is disabled until the fault is corrected and acknowledged.

Root Cause Summary

Safety

Coolant may be hot during operation, allow system to cool before checking hoses or tank
Some coolant products are toxic or irritating, wear protective gloves and avoid skin contact
Do not run spindle without confirmed coolant flow, risk of spindle motor overheating

Causes and Fixes

1
Check Physical Coolant Level
Visually inspect the coolant tank level through the sight gauge or tank window. Level should be above the minimum fill line.
Never add straight water - use proper coolant mixture ratio per machine specifications
2
Verify Level Sensor Operation
Access DIAGNOSTICS > I/O and check the coolant level input status. Toggle should change when coolant level moves above/below sensor.
Clean the level sensor probe with coolant - oil residue can cause false readings
3
Refill and Test System
Add proper coolant mixture to correct level, then press COOLANT button to test system operation and clear alarm.
Allow pump to prime for 30 seconds before expecting full flow

DIY Feasiblehigh confidence

Call a technician if:

·Pump motor replacement required
·Electrical troubleshooting beyond basic connections
·System contamination requiring professional cleaning

Prevention

Maintain proper coolant mixture ratio and cleanliness
Replace coolant filters on scheduled intervals
Monitor coolant level daily and top off as needed
Keep coolant nozzles clean and unobstructed

Common Mistakes

Ignoring gradual flow reduction before alarm occurs
Using incorrect coolant mixture ratios
Bypassing flow switch instead of fixing root cause
Adding water instead of proper coolant mixture

Related Alarms

31 33 719

Seeing Multiple Alarms?

Seeing another alarm with this one? Enter the code.

Get machine-aware diagnosis

AxisMD logs alarms against your actual machines, tracks patterns, and gives AI context your manual doesn't have.

Start free

Was this guide helpful?

Always verify with your machine manual or a certified technician before performing service procedures.