Jeep Liberty defrost blows cold

2011 Liberty. Heat blows cold. Heat comes back
on for a few months. Goes cold again. So we
flushed heater core. Mechanic says climate control
actuator is broken. He got heat back on playing
with dial.  We want to keep heat on so we don't
touch anything. Heat starts blowing cold again.
Now wifey says the dash had a clicking noise near
the climate control and the heat turned back on.
Any ideas greatly appreciated. Thanks!