A/C makes a noise when I press the brakes or accelerator?

Question

There is a knocking noise coming from under the hood. I figured out that the noise only happens when the A/C is on. The noise happens for a few seconds when I first press the accelerator and then it goes away. Then, it comes back for a few seconds when I press the brakes. Any ideas on what this could be?

Answer 1

it will only help to tell us what car or truck you have

but you can have someone get in the car or truck and hold the brake

and give to gas while in gear and look in the engine area and see if you can see anything hitting or rubbing

hope this helps

Answer 2

This sounds like the bearings in the compressor clutch are failing.  You will hear this as the during acceleration and deceleration because the load is changing on the bearings as he engine speed changes.

Answer 3

could you be missing something that is suppose to hold the A/C compressor in place, i.e. bolts for the compressor, or the pulley?

at times, the a/c will cut out when there is a power drag from other critical components and then will resume when there is no longer a load from those components.

Does the A/C work well, could it be low and this is one of your symptoms?

overall, it could be normal, but I would check to make sure that there is nothing loose and that you have a good belt with proper tension on it