Originally Posted by nagata

Ok, hold on a sec, don't go running to the stealer just yet! Does your A/C work fine in normal driving conditions, and then just seems to "turn off" when you press hard on the accelerator, such as to merge or pass? If that is the case, it sounds to me like your system is working just fine, as that's exactly what mine does.

As I understand it, Ford has had an "interupter" in the A/C system on many of their vehicles since at least the late 90s. The way it works is that when the A/C system is engaged and you're driving normally (ie, light on the throttle cruising or gradually accelerating), the A/C system stays engaged. However, when you go full throttle, or at least nearly full throttle, the computer automatically disengages the A/C compressor to give you max power, and will keep the compressor disengaged until you've let up on the throttle. This is just an automatic system for doing what people used to do, manually turn off the A/C compressor when they needed full power, since the compressor is just parasitic drag on the drivetrain.

Now, I don't know how extensive this system is, but I do know that my family has had the following Ford's that all had this auto A/C disengage 'feature': 98 Escort, 02 Focus ZTS, 02 ZX2, 03 ZX2, 06 Focus SES, and 08 F-150 XL V6. I used to regularly drive an 06 F-150 XLT 5.4L 4x4 for work, and I've driven an 03 Explorer 4.0L V6, both of which would do the same thing under full throttle.

My experience leads me to believe that this feature is pretty widespread throughout the Ford line. Perhaps I'm wrong, but what you describe sounds like normal behavior.