PCM C Flow shut down

Hi,
I had faced a similar problem two times, and my findings were as below:

1st time: the issue was in the leaking sampling valve, which was malfunctioning, hence the flow was leaking out of it and hence no flow.

2nd time: it was the faulty PCM module itself. I replaced it, and it worked.

Below are my suggestions for troubleshooting:

1. Check if the septa is leaking.

2. Check and observe the actual flows when you switched on the PC; if they are negative, then try to zero the flow from the configuration; if the limit is beyond the range (in more negative), then you may need to replace the PCM assembly.

Please let me know your findings.

Thank you for your reply. I have not worked much with Gas GCs and I am not that familiar with different parts of it. I have performed leak check around front inlet and inside oven compartments (around columns). There was no leak. Could you please show me with picture where exactly I should look for leak? The system is a Gas analyzer (7890A series). The PCM C has two channels.

Thank you for your reply. I have not worked much with Gas GCs and I am not that familiar with different parts of it. I have performed leak check around front inlet and inside oven compartments (around columns). There was no leak. Could you please show me with picture where exactly I should look for leak? The system is a Gas analyzer (7890A series). The PCM C has two channels.