My 97 Towncar ac blend door actuator started making a clicking noise for several moths until it stop blending the air, caused by internal failure of the plastic gear drive that is controlled electronically inside the "Blend door actuator" that positions the heater blend door in the right position as to divert part of the cold air to the heater core and thus have an output balanced mixed cold/hot air into the cabin. I took the short cut and drop the entire dash panel to be able to reach the Blend door actuator motor that is held by 4-8mm bolts in top of the heater plenum. Boy what a task! I took several photos to illustrate what I did to reach the actuator last 2 bolt too close to the firewall. It took me several hours, but was able to R&R it with a new Life-Time warranty aftermarket actuator bought on Nov 2016 and it work just fine until Now, thus after one year, again I am hearing the same clicking sounds, thus I assume the same gears are failing again, but at least , I know now the steps to R&R the actuator and hope to replace it in half the time it took me before...!