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It's now January and I haven't heard a peep out of the ANC system. Disconnecting the microphones totally worked! I am POed at Ford for not seeing this. It's clear to me that NO ONE at Ford actually knows how the noise cancelling system works. A moot point now that the C-Max has been orphaned.

I pulled the microphone connector last week. I notice the car is actually quieter with ANC disabled which adds credence to my theory that the ANC is enhancing instead of canceling noise.

FYI apparently Wizzurp has found a solution: http://fordcmaxhybridforum.com/topic/6669-how-to-quick-and-easy-reversible-anc-delete/ I pulled the connector he shows but my C-Max doesn't make the noise much in the summer.

Thanks - will try this. My C-Max only makes the noise when outside temp is below 35F. I have long suspected that one of the microphones was wired backwards and instead of canceling noise it is enhanced. My struggles are documented in http://fordcmaxhybridforum.com/topic/3457-strange-long-wooooo-sound-at-steady-speeds-ice-on/the dealer has worked a couple of microphone related changes to no effect.

Could you maybe find out what was updated? My 2013 is still moaning but with the mild winter we've had this year, not often.

The problem with your suggestions is that Ford probably OEM'd the canceller from somewhere and has no control over and little knowlege of how it works. AFIK, Land Rover uses the same module. I would love an option to turn the damn thing off this time of year. My car only makes the noise at a specific engine RPM +/- a very small amount so the panel vibration theory is plausible. It is much more likely to do it if my wife is in the passenger seat but would not act up when I had a dealer tech in the car. Murphy's law. My theory on temperature sensitivity is, when the engine kicks in, it goes to a specific RPM to charge and help out with acceleration. That specific RPM is somewhat temprature dependant. And because the gas pedal is not actually connected to the engine, it's very difficult to finesse the RPM into the narrow range that causes the resonance.

Thirty degree days now and the CMax is starting to make the wooo again.

My wife hates the hatchback. She says other cars are more likely to tailgate a hatchback.

It's confusing to me, the engine only runs about half the time so at 10,000 miles on the car, the engine has only gone 5000 miles running. That's a low mileage to change synthetic oil.

Meagan, It would help a lot to isolate the problem if Ford could come up with a way to disable ANC, preferably as an option setting in MyFordTouch. Pulling fuse 22 disables more than the canceller, it kills the radio too so that is not a long term fix and is not something you can do while moving. I have no idea where the ANC processor is located so can't disconnect it there. If I did know I'd drive a wooden stake through it's heart. We still hear the noise on cool mornings but not when the car is warmed up now that the weather is nice. I'm getting 50 mpg pretty consistantly now.

I had a call from Jeff, the regional Ford guy last week. I told the dealer and him that even after replacing the three microphones, the Wooo is still Woooing. Very dissapointing. He said there is nothing they can do unless the service department can actually reproduce the noise. So far, Murphys Law has been effective. Putting a dealer mechanic in the car suppresses the noise and the weather is now warmer than the car's optimum temperature for bringing it out. I may have to wait until next fall to take it in again. I'm beginning to believe that the car somehow senses that my wife hates it and only makes the Wooo when she is in the passenger seat. I'd really like to know if the noise cancellation algorithym changes when somebody is sitting in the passenger seat. Ford Engineering doesn't seem to know how this thing works - I suspect it is OEM'ed from somewhere. From my googling, it looks like some Land Rovers use the same processor.

Our dealer replaced all three of the headliner microphones on the 16th. It took them a little more than a day, they gave me a rental over the two days. I do not think the problem is fixed. Have heard the noise several times since then, not as loud but it has been warmer lately and it seems to occur most often at outside temps of 25 to 35 degrees. Possible we will have cooler temps early next week and I can confirm for sure, but I'm going to report the problem not fixed next week. Jenie Benson, Ford should be glad to have your car, they can send it to Dearborn and analyze it to their hearts content.

I got word from Ford this morning that they will replace all three of the microphones in my car's headliner. Parts on order. We'll see if that fixes it.

It's the second one down in the center column.Screenshot-CMAX13cmhom3eFord.pdf

Jenie - on a day its making the noise, have your husband pull Fuse 22 in the back. If the sound goes away, than its coming from the audio system.

Taping over the microphones did not make any difference. Tapping on the microphones, as someone else suggested, does cause the noise to fade out. It fades back in as soon as you stop tapping. The microphones are in the headliner. They have small buttons about an inch in diameter with a grill opening. There is one above the drivers head, one above the front seat passengers head, and one behind the rear seat dome light.

I took Dan, the technician that worked the TSB, for a ride Tuesday. Could only get a little of the noise that day but I played the recording through the car stereo and he believed me. They are escalating to Dearborn. We'll see. The tech did show me where the three microphones are. So my next test will be duct tape over the mics.

Good question. The TSB doesn't say anything about speakers so I doubt it. Do you think a car dealer could verify speaker phasing? Would I notice bad sound if one of the speakers was wrong?

That would happen if the microphone element was wired backward internally. Yes, you could reverse the wires or just replace the microphone, but I don't know how you could detect which one is out of phase without a good multichannel oscilloscope which I doubt your average dealer has. My dealer is going to escalate back to Ford, I hope they can get some engineers involved who actually know how the canceller algorithm works.

Dealer worked that on my car and it didnt help at all.

That's the one they worked on Jenie Benson and on my car and it didn't help. DrDiesel posted part of it here last month. That TSB verifyss that the three microphones are wired to the correct harness, but does not check that they are in the proper phase.

I did the last test today. Pulled fuse 22 in the rear panel. There was absolutely no noise with the fuse out, but the bad news is, it kills all the speakers except the one in the middle of the dash. Radio sounds awful but it confirms the wooo is coming from the sound system.

The most PRACTICAL fuel efficient speed is whatever is required to get your transmission to shift into overdrive. On my 09 Focus that was about 42 MPH.

Fair Oaks Ford worked TSB 14-0151 today on my C-Max. They said they did not find any problem with the wiring and they caulked up the microphones. As Jenie Benson reported though, it did not fix the problem. Heard the moaning three times on the way home. I have verified the noise stops if you open the door, and it does seem to stop if you open a window. Nest test will be pulling F22 in the rear fuse panel.