Loud squealing/chirping noise

I have the same issue, with the same year and model. I replaced the tensioner, the idler pully, the alternator, ac compressor, fan clutch, water pump, andd 3 belt. Same result everytime. I did notice thatm, and you may want to look at the pully on the water pump, and see if the belt is going crazy, with a wobble backk and forth on the pully. This is where my chirp is coming from. If I get a long screw driver and push the belt over where it is supposed to be, the chirp goes away. I took my explorer to the shop this morning, at ford. I will repost when they call me with the problem, in the mean time, check out the water pump pully and see if you belt is moving back and forth on the pully.

The dealership got done with my truck and said it was the harmonic balancer. They put a new one on, 401.99 cents. But can be changed yourself with a new one at Autozone for 89 bucks. I should of went this way too, but wanted a garantee it will fix it when they changed it. Good luck and keep us updated

Was your problem resolved by replacing harmonic balancer?

Yes it fixed the problem, been about 2 weeks and is running great now. Not a single churp since replacing it.