Hi all,

This is a first post from a long time lurker here. I am hoping to solve a problem that has kept me in the weeds for awhile.
The CCU (pushbutton climate unit) is shutting down after a few minutes, going into a safe mode. When this happens, the vacuum port valve under the dash is going crazy, clicking randomly, and then the led light on the recirculation button flashes steadily (I guess to let me know that the system is protecting itself).
If I am running heat, this is much less likely to happen than when the temperature wheel is set to cold.
I was able to get the car connected to a Mercedes computer (16pin) and it gave no HVAC codes even during the 'episode'.

Any help would be greatly, muchly appreciated.
Thanks.

Just to clarify.
Monovalve works
#7 fuse good
Wires under#7 were cleaned and greased with dielectric grease
AC compressor and aux fans functioning properly.
Flaps, with the exception of the center vent seem to be working.
Recirculation button does nothing at any time except when the light flashes..