Well for years when I turn on my AC from On to Max I get this knocking sound that last about 15 seconds then goes away.

It never comes back unless I switch between settings from MAX to Regular or Regular to Max.

The air blows but the AC doesn't kick in until after that 15 seconds and the knocking stops.

Any Ideas?

2005/Roush

 

generaly the max setting closes the loop so that the air is recirculating inside the car, with the fan on high, does switching between closed and open cause the same sound. I'm not sure on my 08, if I was able to even switch from open to closed loop aside from in "max" ac, might be a problem with the flapper that controls open and close to outside car.

 

Blend door actuator.

 

ty, I was talking in generals didnt know what the part was called.

 

Likely this one:
http://iihs.net/fsm/?dir=336&viewfil...20Actuator.pdf

But while it's bangin', try to find out from exactly which of these area it's coming from to figure out which actuator is FUBAR:
http://iihs.net/fsm/?dir=336&viewfil...20Actuator.pdf
http://iihs.net/fsm/?dir=336&viewfil...oor%20Door.pdf
http://iihs.net/fsm/?dir=336&viewfil...let%20Duct.pdf (listed part 5)
http://iihs.net/fsm/?dir=336&viewfil...let%20Door.pdf

Easiest method, would likely be to disconnect one at a time, and check if the noise is still there. That'd be the one to yank and replace.

 

Ahh awesome this is perfect! I will do work on it this weekend and update you all!

Thanks everyone for all your help so far

 

Be confident in this one - definitely the A/C blend valve (behind the dash). Happened to me.

 

I'm experiencing the same issue, once the ac goes on it clicks for a few seconds then stops. it wouldn't bug me if it wasn't a loud click. does anyone know how much an actuator costs?

btw did you check it out nfordhk?

 

Around $20-$60 depending on where/who you get it from. All 3 use the exact same actuator(OEM). Note part #'s. Just yank the connector from each, one at a time til you can verify the auditory offender.

Something, again (from other thread) you probably want to check the price/avialablity of at the local auto parts store(autozone, etc) before you buy from the local dealer, as OEM isn't the only way to go for this.

 

There are THREE blend door actuators on these cars. I think 2 are on the passenger side, and one on the drivers side. I think I paid about $20 for the ones I bought. I actually had 2 to go bad at the same time, and the worst 2 at that. I had to take the airbag out for the one on the passenger side, and the one on the drivers side...well, I did some things that I'm not totally proud of with a pry bar, but I was able to finally get it in without having to take the dame whole car apart. I pulled the speedometer out, and with a pry bar, pryed the dash up far enough to get my big hand in to get to the two screws.....I'm not sure how else this would be done.

If you're lucky, it's the lower one on the passenger side that can EASILY be reached.....