I had no issues with the A/C system until one day it appeared that the vents were not blowing very much cold air. The temperature control was turned all the way to cold and I turned the fan all the way up. Roughly 10 minutes later, the air had cooled off to normal levels. I stopped the vehicle and went into a store, and when I came back and started the vehicle, suddenly there was a constant knocking noise coming from inside the dash, directly behind the radio. Just like the Terminator from the 1984 movie, it DOES NOT STOP. EVER. I can change the temperature to hot, and turn down the fans, and it's still there. I can even turn the climate control system off entirely, and the knocking is still there.

Online research reveals that it is probably a malfunctioning blend door actuator, which is located behind the radio. I have ordered a new part and will be attempting to put it in myself soon. It might be worth noting that this knocking started very soon after I had a brand new battery installed in the truck. Maybe 10 miles or less after I left the auto parts store where I got the battery. I doubt that has anything to do with anything, but you never know.

Like the other complaints, the AC starts clicking when the temperature selector is set on the coldest setting. Dial it down a bit (warmer) and the noise goes away. It's a problem in the heat of a Texas summer. Am investigating fixes.

Update from Jul 21, 2017: Online search shows Ford vehicles have a problem with blend door actuators going bad. Parts are cheap (obviously) but somewhat involved to access. See these videos: https://www.youtube.com/watch?v=zNfnwJART6w https://www.youtube.com/watch?v=p5xvlbiaxF4 https://www.youtube.com/watch?v=6hM4PTJ8PNs https://www.youtube.com/watch?v=42oa17lFU5I https://www.youtube.com/watch?v=EbTivF3Mp8I https://www.youtube.com/watch?v=D-M30Kyyykc

I have just replaced the original (from the factory) battery. Upon starting the engine for the first time with the new battery the vent control doors behind the dash keep clicking and the heat/AC is stuck on the coldest setting (regardless of where I place the manual control knob) and is set to defrost. None of the Heat/AC control buttons or knobs work except for the fan speed control and the system on/off switch.

Even when the heat/ac system is turned off the vent control doors continue to click repeatedly until I turn off the ignition switch.

Does anyone have a solution? Serious and helpful responses only please.

ac and heat started as a clicking noise, then started putting out just cold air on passenger side. looked up other complainants and there are a lot of them. contacted ford motor company and was just told there currently no recalls but if at a later time there is they may reimburse for us paying to have fixed. its sad to pay 60,000 for a truck which by the way is a limited edition and when you take to a ford dealer ship they rip you off in the service department. the mechanics are paid by the hour of course so they take their coffee breaks and any thing else they can do to run the bill up so a 50.00 dollar piece just estimating turns into a 400.00 to 500.00 bill our solution is dont buy a ford

Earlier this year while on a road trip, I attempted to change the heat selection to cooler air rotating it all the way to the blue (cool) side of the knob. When I did this a clicking noise could be heard coming from behind the radio area that would not stop until I rotated the knob back toward the warmer (hot) side of the control. Now I noticed that I can avoid the noise if I don't run the air conditioner set at the higher or coldest point of the blue setting. This is annoying! I'm amazed that such a condition occurs at all.

My F-150 has two blend air doors. The part to fix it is made of plastic and dealer price is $18.00. If the passenger side door needs to be fixed it is inexpensive, but if driver's side goes bad, you must remove the whole dashboard to access the problem and labor cost run up the cost to $800.00 to $1,000.00....RIDICULOUS !

My son has a 2008 Expedition and he has had the same problem....Ford has decided to go as cheap as possible on the initial cost to save a few dollars and then causes the consumer to bear the burden of the expense when the part breaks and is past the warranty period.