I have a 2008 F-150 60th anniversary edition and when the AC is on there is a knock on the passenger side floor. The only time is happens is when the AC is on and doesn't do it when the AC is off. Can anyone help me with this?

 

i have the same problem 2008 f150 lariat

 

I'm not sure. Does this happen with max AC or just AC in general? Too me it sounds as if maybe the blend door is not operating correctly. Why don't you check it out?

 

same with my 2008 Screw FX4 I can hear it louder when the AC is lower. I think someone else on here said it was the fan for the ac but not sure.

 

i'm taking my truck in next week i'll keep you posted thanks for the reply

 

let us know what the shop says, my 08 fx2 does the same thing, its pretty loud when u get out the truck and here it