Troubleshooting a Thermal Shutdown Error on a GC System

Answer

This Information Applies To: Agilent GC systems

Issue

When a GC heater cannot reach setpoint, or taking too long to reach setpoint, the GC will enter a "Thermal Shutdown" (or similar heater error) state to protect itself. This state will turn off all the GC heated zones (inlets, oven, detectors, valve box, MS transfer line). Sometimes the error or GC status will specify which heated zone has failed, but it is a better practice to isolate which heated zone is triggering the error.

Steps to Follow

1. First, clear the error. A quick method is to reboot the GC and promptly turn off all heated zones before the error reoccurs. Alternatively, you can turn off each heated zone as follows:
   
   • For an 8890 (or 8860 via the Web User Interface): On the Diagnostics tab, press the red icon, view the error, and clear it.
   • For a 7890/6890 GC: On the GC keypad, Press the button corresponding to each heated zone and scroll down to the temperature line. The temperature value will flash Off. Press the [Off/No] button to clear the error.
   • For a 7820: If available, use the 7820A GC Remote controller software. Click the button corresponding to each heated zone and scroll down to the temperature line. The temperature value will flash Off. Click the [Off/No] button to clear the error. If the 7820A GC Remote controller is not available, use the acquisition method editor in the controlling software to turn off all heated zones.
   • For a 6850: If available, use the plug-in Control Module. Otherwise, use the acquisition method editor in the controlling software to turn off all heated zones.
2. Once the error is cleared, turn on one of the heated zones. If it heats up to the setpoint without triggering an error, it is working correctly.
3. Turn off the heated zone from the previous step.
   

   Tip: The normal behavior of inlets, detectors, valve box and MSD tranferline are that they will heat up and then cool down slowly.

4. Repeat this process with each heated zone. You will find that one heated zone will either overheat, or struggle to heat, triggering the error. Communicate your findings to the local Agilent support representative.

Oven thermal shutdowns

If the oven is triggering the thermal shutdown error, do the following:

1. Clear the error
2. Set the oven to a temperature slightly higher than room temperature (i.e. 50 °C).
3. Open the oven door and confirm that the fan rotates. It should slowly come to a smooth stop.
4. Close to oven door.
5. If you have access to the back of the instrument, check that the oven flappers are working properly (See Figure 1).
   1. Set the oven to a temperature slightly higher than room temperature (i.e. 50 °C). The flappers should close
   2. Set the oven to a temperature below room temperature. The flappers should open.
      

      
      
      Figure 1. Flappers location
      
      

6. Communicate your findings to the local Agilent support representative.

Learn how to effectively troubleshoot your Agilent GC system: Agilent 7890 Series GC with OpenLab CDS Agilent 8860 GC with OpenLab CDS Agilent 8890 GC with OpenLab CDS e-learning paths available from Agilent education