Service Home Through-Tool Air Blast (TAB) - Troubleshooting Guide - TG0145

Through-Tool Air Blast (TAB) - Troubleshooting Guide - TG0145

15.3 TAB - Troubleshooting

Last updated: 10/15/2025

Through-Tool Air Blast (TAB) - Troubleshooting Guide

TG0145

Revision C - 10/2025

Shuttle & Ball - TAB Check Valve - System Diagram

 
  1. TAB Air Check Valve - This check valve prevents coolant from entering the CALM system.
  2. TRP Air Blast - This line provides air during a tool change or when TRP unclamp is activated.
  3. TSC Purge Valve
  4. TSC Pump
  5. Compensating Union
  6. Analog TSC/TAB Pressure Sensor

Spring & Ball - TAB Check Valve - System Diagram

  1. TAB Air Check Valve - This check valve prevents coolant from entering the CALM system.
  2. TSC Purge Check Valve
  3. Air Blast Check Valve 
  4. Coolant Check Valve - This check valve prevents coolant or air to backflow into the coolant system.  There is a spring and ball inside this check valve.  
  5. TAB Air Valve - This solenoid turns on when TAB is activated.
  6. TRP Air Blast - This line provides air during a tool change or when TRP unclamp is activated.
  7. TSC Purge Valve
  8. Spindle Air Valve
  9. Analog TSC/TAB Pressure Sensor
  10. TSC Pump
  11. Compensating Union
  12. High Pressure TSC Coolant Hose

Built-in - TSC/TAB Check Valve - Diagram

  1. TAB Air Check Valve - This check valve prevents coolant from entering the CALM system.
  2. TAB Assembly
  3. TRP Air Blast - This line provides air during a tool change or when TRP unclamp is activated.
  4. TSC/TAB Compensating Union
  5. To Spindle connection
  6. Drain Assembly
  7. TSC Pump
  8. Spindle Air Valve
  9. TAB Air Valve
  10. TSC Purge Valve
  11. TSC Purge Check Valve

Symptom Table

SYMPTOM

POSSIBLE CAUSE

CORRECTIVE ACTION

Alarm 2081 LOW TOOL AIR BLAST PRESSURE

Insufficient air supply to the machine

Verify that we are meeting the air supply requirements. TAB consumption ranges from 8 to 15 cfm (0.226 to 0.425 cmm). Alarm occurs when pressure drops below 30PSI.

NOTE: Machines with software version 100.22.000.1000 or later will cause an alarm to occur when pressure drops below 15 PSI.

Tool orifices are too large

Verify size of tool orifices. Add a restrictor to the tool orifice. Or add a pull stud with a smaller diameter through-hole as a restrictor.

Compensating union defective

Verify the compensating TSC union, especially whether the piston is stuck

Defective TSC pressure Switch

Verify the LOW TSC bit in diagnostics as TAB uses the same pressure switch.
The check valve (spring & ball check valve only) is stuck internally. See the Check Valve Inspection section below.
VF-Small and Medium Machines (VF-1 through VF-5) built between 3/15/2023 and 5/19/2023 may not have the new slotted elbow fitting in the new TAB check valve.

Verify if the new TAB check valve has the new slotted elbow fitting. If the new slottled elbow fitting is not installed order PN 20-10157 and install it.

HSG-A 5-24-2023
Tool Air Blast (TAB) on DC-Series machines has low air flow DC-Series machines built from 4/7/2025 - 11/1/2025 have a 0.040" orifice fitting on the TAB solenoid assembly. Remove the orifice fitting from the solenoid. The TAB solenoid on DC-series machines is connected to the TSC Purge connector in the lube panel. See the section below on removing the orifice.
Tool Air Blast (TAB) causes coolant tank overflow. The coolant check valve (spring & ball check valve only) has failed. Troubleshoot the coolant check valve. Refer to the Coolant Check Valve section below.
Coolant fills the TAB air pneumatic line and blows out the muffler in the CALM cabinet. The TAB air check valve (spring & ball check valve only) has failed. Troubleshoot the TAB check valve. Refer to the TAB Air Check Valve Inspection section below.
TAB solenoid does not operate when commanded. I/O mapping needs to be updated for machines built before June 2019 and have the Programmable Air/Dual Programmable Air or VF Small Auto Window option on their machine. Contact Haas Service to have a patch applied to enable the TAB option.
Air bubbles observed in the coolant tank. The TAB air check valve is faulty. Troubleshoot the TAB air check valve. Refer to the TAB Air Check Valve Inspection section below.

Coolant Check Valve Inspection

Shuttle & Ball

This check valve has a ball deflector [2] inside rather than a spring. The ball deflector acts as a shuttle by directing the ball from one location to another--either blocking the coolant or TAB opening.

As coolant flows into the valve, the ball gets pushed and deflected out of the way [3]. When TAB air flows into the valve, the ball gets pushed back down due to both air and gravity [4].

The new shuttle and ball check valve also has a new elbow fitting that is slotted [1]. This elbow fitting allows a small amount of coolant or air pressure through to pressurize the pressure sensor.

Spring & Ball

Coolant pressure can push the ball into the spring and trap it, causing the check valve to fail.  Without a functional check valve, air from the TAB may flow backward through the coolant system and cause the coolant tank to overflow and/or bubble. 

Corrective Action:

Disassemble and visually inspect the check valve for any deformities. Make sure the ball isn't trapped inside the spring. If it is, the spring would be pushing the ball against the countersink of the fitting.

TAB Air Check Valve Inspection

When the TAB air check valve [1] fails and TSC is turned on, coolant from the TSC pump will back flow through the TAB air line to the solenoid and blow out the muffler.


CORRECTIVE ACTION:

Replace the TAB air check valve.

DC-Series Through Tool Air Blast

DC-Series TAB Option:

Remove the 0.040" orifice fitting [1] from the TSC Purge solenoid assembly [2]. The orifice is located after the checkvalve [3].

After the orifice is removed, test the TAB option again.

Electrical Schematic

1

TAB Solenoid Output:

Go to DIAGNOSTICS and observe as:

  • Air blast is triggered, Output 43 Through Air Blast Union should be 1 [1] and TAB Icon appears [2]
  • Air blast stops, Output 43 Through Air Blast Union should be 0.

If TAB still doesn’t act as expected, check the connection between the solenoid assembly. Ensure the solenoid assembly is connected to the Air and Lube cable 33-9085F that plugs into the I/O board at P35.

With the cable still plugged in, use fine tip probes to check readings between Pin 35.20 TAB and Pin 35.19 Ground to measure the amount of voltage the TAB receives. The expected voltage should be around 110 - 120 VAC.

2

TAB Analog Sensor Input:

Go to DIAGNOSTICS and observe as:

  • Air blast is triggered, A-Input 7 HPC TSC Pressure should increase in value.

If TSC pressure sensor still doesn’t act as expected, check the connection.  Make sure the pressure sensor is connected to the M12 cable that plugs into the I/O board at P39. The TSC Analog Pressure connection is Pin 39.21 and the Analog Ground connection is Pin 39.27.

3

Test TAB Analog Pressure Sensor with Multimeter:

You will need to remove the spindle head sheet metal panel to gain access to the spindle head inputs bracket. The machine must be powered on and at idle. Locate the M12 to 2x2 TAB pressure sensor cable. With the able still plugged into the spindle head inputs bracket, use fine tip probes to check readings between pins. Refer to the table below for the correct readings. If the values are not within range, the TAB sensor is likely to be faulty.

Red Multimeter Lead Black Multimeter Lead Expected Reading
Pin 2 Pin 1 4.75VDC to 5.25VDC
Pin 3 Pin 1 0.490VDC to 0.510VDC (machine is at idle)

TAB Test

1

Make sure the TAB system operates correctly.

Insert a tool with an orifice into the spindle.

Operate this code in MDI mode:

M73;

G04 P5.;

M74;

G04 P3.;

M99;

M73 starts the TAB. M74 stops the TAB.

Manually operate the TAB:

Press [SHIFT]. Press [AUX CLNT].

The tool air blast starts.

Press [SHIFT]. Press [AUX CLNT].

The tool air blast stops.