There is a drip in the passenger side whenever the A/C is on in my GXP. I have no idea what the HVAC system behind the dash looks like, but I assume there is a condensation drainage tube that runs behind there. I have a feel its been plugged up somehow.

 

Has anyone had any experience with getting back there on these G-platforms? Its it a relatively DIY task getting back there or is it a complete pain in the ass?

Anytime you deal with the HVAC/heater core system, it's a pain in the arse. You first have to remove the A/C ducting, and on some cars you sometimes roll back part of the carpet, just to gain access to the HVAC box itself. The leak could be coming from the heater core and if that's the case then the situation becomes even worse. So clearly inspection is warranted. Let's hope it is a simple fix.

Find the drain hose through the firewall for the HVAC.  Run a coat hanger through it.

11 hours ago, notallthere said:

Find the drain hose through the firewall for the HVAC.  Run a coat hanger through it.

Words of wisdom to check 1st.  Hope its not the core as Frosty said.