Hi All. Searched high and low around the forum here (great information!) and found some guidance for my problem, but still need some help. 2002 Explorer XLT with manual HVAC. Clicking/thumping coming from driver side rear quarter panel. Sound volume and character (*THUMP* or *click*) seems to vary with temperature setting for rear climate controls. Don't notice any difference between rear setting for upper or lower vents in the back. Figure I've got a temperature blend door actuator problem in the back (based on other posts here). I understand there are two actuators -- one for temp blend and one for air distribution (top or bottom vents in the back seat). So far, I've removed all of the interior panels and rear seatbelts to expose the entire rear heater core housing (pardon if my terminology is poor). Still can't see the actuators, though -- I assume at this point that they are mounted on the back of the housing (between the metal outer quarterpanel and the housing). Questions: (1) How do I get to the actuators?! I see three mounting bolts that seem to secure the housing to the body. But: there are clearly a number of hoses and tubes that run into this assembly from underneath and behind. Some other posts seem to suggest simply disconnecting the electrical harness connections, removing the three mounting bolts, and pulling the entire housing into the rear compartment for access to the back and the actuators. Do I have to drain the refrigerant from or disconnect all of the hoses to do that? Nobody seems to mention it, so maybe it's possible? Please advise! I'm nervous about pulling something apart by mistake. (2) Assuming I can get to them, should I just replace both actuators, or is there a definitive way to tell which one is bad? (3) Anything else to check -- is it possible that something else besides the actuators is the problem? Maybe the blend doors themselves? How would I inspect? (4) Are the two actuators (heat blend and distribution blend) identical -- same part number? I've seen some prices online that suggest they are different. Any guidance will be MUCH appreciated. I've gotten this far thanks to other posts here. Thanks in advance for advice!