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A/C cuts out when accelerating

I have a problem with my 2007 Mercury Grand Marquis. Whenever I press down on the accelerator, whether just picking up speed or going up a hill, the stream of cold air coming from the air-conditioner stops. This lack of A/C typically lasts 12 to 15 seconds. In the hot summertime, you can be sweating by the time the air-flow resumes. Somebody told me this happens because the designers thought if you were accelerating, you probably need all of the power of the engine, so the A/C compressor stops running to allow the engine power to be full-bore. Whether or not that is true, is there some way (some adjustment under the hood) to prevent that from happening? I would like the flow of cool air from the A/C to be continuous, not affected by whether or not I am pressing down on the accelerator.

Well, it may be that the compressor cuts off under heavy acceleration, but I would suspect a vacuum problem letting the blend doors to close.

Your car sounds like it is operating exactly as designed. When you mash down the go pedal, the TPS (throttle position sensor) gives the WOT (wide open throttle) signal to the PCM to momentarily cut off power to the A/C clutch which disengages the A/C. You can probably prevent this from happening by not mashing down quite as hard on the go pedal, thus preventing losing your cooling. You should practice for a while and you’ll eventually be able to find the spot with your foot where you get as much vehicle speed whether you are mashed down all the way, or 4/5 of the way, thus preventing the WOT condition. I would not recommend modifying your vehicle so the A/C doesn’t cut out. You might just need or want that little extra burst of power when you find yourself passing a truck going up a long hill on a blind curve.

The AC compressor cut off is at WOT (pedal to the floor) only.
Does the airflow continue and get warm, or does the airflow stop or switch to the defroster outlets?
If the airflow stops or switches, then you have a problem either with the vacuum check valve to the AC system, or a vacuum leak after the check valve.

The blend-air door is controlled by an electric motor. (The blend-air door controls temperature.) The air direction dampers are controlled by vacuum.

I understand that the WOT cutout is more for preservation of the FEAD belt than anything else. WOT shifts are hard on it so briefly removing the load should help. A lot of things changed in 2005 when the throttle control went from cable to electronic. There is a built-in throttle trim that accompanies shifts. Some find it annoying, but it probably saves on transmission clutch material. Almost all these things can be changed by someone that does custom PCM tunes, but it will be costly. I am not sure about 2007s, but earlier models could probably be modified by monkeying with the AC WOT cutout relay.

The OP definitely needs to answer the questions, it this at (near) WOT only, and is it a temp change or an airflow redistribution. It does, however, seem like it is not acting normally.