Join Date: Dec 2008
Location: norman, ok
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constant light tapping noise? I have dealt with many of these in the last couple of years and I would bet its one of the actuator motors for the HVAC.
A little test you can do is slowly move one setting at a time on your HVAC, (i.e. pass temp, then drivers side temp and so on). Move a temp setting one at a time and see if the noise goes away. If the noise goes away then its probably that actuator.
I have replaced many of these actuators for this concern and they are not always for the temp door(s) but most of the time they are. Seems the passenger temp actuator has a little more popularity for failure
Most actuators can move around 90* of travel, some basically move all the way one way or the other, the temp actuators can stop at any position. Basically what going on with the actuator is they have a position sensor inside the unit (much like a TP sensor) the position sensor gets dirty or develops a bad spot in it, so the motor cycles back and forth over the "bad spot". Its basically searching for the right spot which causes it to "twitch" and make the noise.
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