If anyone hears a tick tick noise when their heat is on a low setting I hear it is because your cabin air filter needs to be changed. So that is what I see online. I have had this, I figured something was brushing up against the fan...so I ordered a new cabin air filter...Ill let you guys know if it goes away...

 

i had to have my entire heating unit replaced the other day... had the same noise you did.

 

well then, lol...Thanks for the warning!