Recently my heater stopped blowing super hot like it used to. It feels like the thermostat failed but the engine temp gauge is in the spot it's always been in (if that's an indicator of anything). When I turn the heater on, I can hear a constant, repetitive clicking noise coming from under the dash on the passenger side. Any ideas what this could be?

 

All models after 1996 have a servo motor that adjusts the damper and pulls the cable to turn on the heater water valve under the hood.

If the valve or air box vane is stuck it would cause the clicking sound from the servo motor.

http://www.ncttora.com/fsm/1996/SIL/...eauni/comp.pdf (diagram of the air box control system)

 

That has to be what it is, cause I get no air to the floor anymore and it's not coming from the blower fan but rather the center of the dash. Are there any writeups on how to fix it or just how to take the dash apart?