loud tic

Well... you might try to localize where the tic is coming from. When my MIL was alive, every now and again I would get a noise from the back seat... I finally figured that one out with a little deduction...

front or rear ????????

Sounds like blend door motor or door broken

hi the tic is comming from the front of the engine.. only when i put the heat on.. not a/c or do anything else. it sound like a switch of some sort. i get lots of heat and cold and lots of air front and back thanks

Well, the first thing that comes to mind is the AC compressor.... Any time that air blows on glass, the AC will run to dehunidify the air to avoid fogging. On yours, there are very few heater positions that will avoid having this happen. Now... since the tic comes so often, I would suggest that the refrigerant level in the system is low.... even though winter is approaching, it is usually cheaper to have problems addressed early in the process rather than waiting for a catastrophic failure capable of redesigning our budgets.

Are you making a living as a service writer ??????

Could have used that info in your 1st message.

anything else you left out ?????????

No problem, just try to put in as much info as possible that might be related.

when ,where, hot ,cold,idle , under acceleration etc.

like Jim said, fast cycling is usually a sign of low on refrigerant

Hope you find what's wrong withit

Did you find out the problem? My 2001 Ford Explorer just started doing the same thing. It tics every 5-8 seconds with the heat on only and when it happens, the idle drops about 200 rpm.