06 Expedition Noise

i have a ticking sound comming from the right rear. ticking is constant when i am moving and not moving. about onbe tick per second. very annoying i can hear it from inside the vehicle. any ideas?

thanks

Try turning off the rear ac unit and see if the noise goes away.
i have a 2003 and that noise come up and it happened to be the door actuator for the ac blender.Hope it helps.