This just started today for the first time. I turn the AC on and I hear vibrating noises under my right dash and it gets louder as I turn it up. Of course it stops when the AC is turned off. What the hell can this be and is it expensive to get it replaced/fixed? I have a 99 f150 supercab 5.4 V8. I cant recall any problems with my AC. Help is needed ASAP because its hot down here in Austin TX! Thanks

 

Sounds like the blower fan. If you turn the system on vent will it do it too?

 

Yes it does, does it on defrost and everything. Is this anything or the same as the blend door that I keep seeing all these threads about? Im wondeing what it would cost and etc. I hope its not the blend door or heater core whatever that crap is that everyone is talking about. Im to the point to where I want to trade this damn truck in. what should I do?

 

Is my truck supposed to smell like something crawled in the truck and died? I jump in my truck after sitting for 7 hours while I was at work and all of a sudden, it smells like something died. Nothing was on for that whole time. And when I turn the AC on, I smell it even more. Its smells like *****!!! WTF is wrong? Is that free-on?

 

Check the front cowl and make sure nothing is down there.

I had friends that would poor milk down there, which is the location that the AC pulls air from.

 

What and where is the front cowl? Im sorry if I dont know what that is.
Thanks. How would I check it?

 

Did you ever find out what was wrong? I have the exact same problem right now and I think there may be a dead mouse stuck in my blower. I've already taken the dash out and plan on moving ahead tonight.