Welp, same problem for me, so I thought I'd bring up the thread again. Hoping someone maybe has a service manual diagram of this setup?
'07 RT. I have no heat on the driver's side, blows perfectly hot on passenger's. If I switch over to cold, the driver's side says cool, the passenger's side stays kinda luke warm.
All modes work correctly. I have regular HVAC, not dual climate. If I go Defrost, driver side Defrost is cool. Just like many others in the thread.
If I operate the temperature knob, nice and slow, I can see the temp actuator over the gas pedal move. I don't hear any clicking/slipping or other weird noises, however I don't know for SURE that it has full range of motion. I don't know how to tell.
Is there more than one temperature actuator on the non-dual-climate Ridgeline? Would taking apart the temp actuator and cleaning and re-greasing it possibly help? Anything else I can look for?