Column flow/pressure drops during desorb

Can you share some screen captures from MassHunter Acquisition with your run method loaded of the  Inlets SSL-Front (or whichever one your P&T is connected to), GC Columns window, the Configuration/Columns window, and the Configuration/Modules window?   It could also be an issue inside the P&T. During desorb a valve inside the P&T puts the trap inline with the flow to the inlet while the trap heats up to desorb your compounds. If the valve is not working right, the trap is plugged or leaking, or a few other possibilities, the pressure/flow to the GC inlet won't be present.  

Does the GC work fine without running the P&T?  If you just setup and start a run by pressing the start button, does it run?  

Please see the attached. I however as a routine maintenance of P&T rinse the sample pathway. After that i baked the system. Could i have done something wrong amd if yes how could i rectify. 

I have put a beaker with methanol at the end of the transfer line from the P&T and manually desorbs and i could see bubbles in the beaker. Couldn't this mean the p&T desorbs correctly? 

I have put a beaker with methanol at the end of the transfer line from the P&T and manually desorbs and i could see bubbles in the beaker. Couldn't this mean the p&T desorbs correctly? 

Yes, probably. But that's with no restrictions on the outlet like the GC inlet, liner, column, column connection, transferline connection, etc.  You can get flow with no outlet back pressure and no flow with it.  What is the carrier supply pressure to the GC and P&T?  The pressure at the transferline outlet must be able to reach at least 63kPa (9.2psi) there.  Any pressure regulation/flow controller needs to be around 140kPa higher than the total of what is downstream of it.  At your final oven temp the inlet is ~164kPa (23.7psi). The trap and plumbing is a restriction, the EPC module, too, so you should have your supply set to at ~482kPa (70psi) or so.  If the gas line filter is plugged up a bit, your trap plugged up a bit, or you have any further restrictions it may required higher pressure than that.

If this started after you did P&T and column maintenance, I would suggest you go back and do those again to make sure they're as expected.