Got a problem with my A/C. First I took it to the dealer and they advised it was the compressor, replaced that. Then it was a front radiator fan motor, replaced that. Both did not fix the problem. Dealer now wants to replace the A/C blower motor regulator switch... Don't really have trust in them now. Oh and cabin air filter was replaced.

Problem: A/C is making a humming sound that has gotten louder. Sounds like it is coming from inside the cabin area not engine bay. The hum is close to what sounds like a lawn mower if you passed one with the windows up. The A/C is cold and blows, but it does not seem to have the same air flow force as it should. At high it blows more like on med/low. And every once in a while, the A/C will suddenly start to blow at the correct force then slow back down.

2011 M37x with about 36,000 on it.

Any help would be greatly appreciated! THANKS

I wonder if it is the air con fan motor itself or a sensor / switch that works the air con fan. Please let us know how this ends.

Because it has a humming sound, my guess is the fan motor is sick. No sounds then I would steer more towards control such as the regulator switch.

Yeah my guess is fan motor too. WTH would they replace the compressor, lol.

Sounds like some debris may be stuck in the Blower Cage. Was the Cabin Filter replaced before or after the noise began? Maybe a leaf or something fell from the filter while it was being changed. Fan motor is a strong possibility as well as previously stated.

One quick question... Do you have the Forest Air Option? I ask because it blows air at random/varying degrees of intensity to act like a breeze.

I also had an AC sound issue but did not have the problem with the blower.

The only 2 moving parts of the A/C system are the compressor and the fan-blower-motor. The compressor is in the bottom of the engine bay, the other is in the firewall blowing air directly into the cabin. So if it sounds like it's in the cabin, it's gotta be the blower motor. That's also consistent with the reduced air flow. A bad compressor cannot possibly affect the force of air blowing out the vents. Only a blower motor affects that. So, all clues point to the blower motor. And if it's not the blower motor itself, the problem might be in its control circuit. Good luck!

one more vote for blower motor. Just had a similar issue on my quest. Noise in the cabin and a bit reduced force of the air coming out of the vents. Turned out, the blower motor bearing was bad. Had to have a new motor put in.

Does the humming sound increase with the fan spinning faster (when you set the fan to high does it get louder?) If so, the blower motor for sure.

The dealership and I had a long poor decision talk about why they did the compressor. Still fighting them on that issue.

Yeah my original guess was the blower motor. Had a similar thing happen to another ride several years back.

The noise does increase as I increase the fan speed. I did change the air filter and clean the system to ensure no debris got in so that's out. I do have the forest air option however it's not on when I have this problem... Is there more on that avenue that could cause this issue?

So I'll be purchasing a new blower motor and looking to install it myself hopefully this weekend. The noise is driving me nuts.

Thanks for all the suggestions and I will let everyone know how it turns out.

albqglock wrote:The dealership and I had a long poor decision talk about why they did the compressor. Still fighting them on that issue.

Yeah my original guess was the blower motor. Had a similar thing happen to another ride several years back.

The noise does increase as I increase the fan speed. I did change the air filter and clean the system to ensure no debris got in so that's out. I do have the forest air option however it's not on when I have this problem... Is there more on that avenue that could cause this issue?

So I'll be purchasing a new blower motor and looking to install it myself hopefully this weekend. The noise is driving me nuts.

Thanks for all the suggestions and I will let everyone know how it turns out.

While you're at it, if you could create a howto, the community would appreciate it. Use one of mine as a template (see sig). Thanks! lol

This will be a VERY involved project. Starts on page 45 and involves evacuating the refrigerant and removing the dash.
http://www.nicoclub.com/FSM/M/2011/HA.pdf
http://www.nicoclub.com/FSM/M/2011/IP.pdf - dash removal starts on pg 12

I've thought changing out my heater core due to some heating issues, but it might be worth it to have someone else do it.

Alrighty... Problem RESOLVED!

Thank you everyone who suggested the blower motor cause that was the problem. On that, here is what I did for those that might come to the same problem.

Couldn't get a good recording of the noise, but it sounded like a lawn mower was constantly being ran outside of the cabin. The sound would totally stop if the A/C was turned off. It would also get louder depending on the speed setting additionally I was experience air flow slow down with random bursts of increased speed.

https://www.youtube.com/watch?v=ONlbh_t2irs

I suck at videos but here is a great video that will get you 95% of the way. In the video it shows you where the blower motor is and helps you replace the cabin air filter at the same time if needed. On that note here is my how to...

1. Remove the glove box, really not hard. Open it, extend it about 90% open and pull. Give it some force due to the snap ins are usually tight. There are three so I suggest more force to the far right to start.
2. The glove box has a tension cord attached on the left side (driver side). If you tug at it with a little force it will pop out due to it just being a snap in. Once this is out you can remove the glove box completely.
3. Below the glove box is a bottom plastic floor plate that houses a light. This plate is a snap in so just pull it down and it will unsnap. There is some electrical wires to a plug on this plate. Unplug it and put this plate aside.
4. Now to the right of the glove box area is a plastic cover, should be the color of you interior. This pops off if you pull at it.
5. You now have full access to the glove box housing assembly that is held in place by seven screws. Unscrew them and pull on the housing and it will come out. The housing has some electrical attached to it. I could not get these electrical attachments to pop off. I used a screw driver and some force it see if I could get them to pop but felt they would break before they popped. So I moved this housing off to the side which allowed enough access room.
***All of the above is greatly shown in the video link attached***

At this point the video goes to removing the cabin air filter, but does show you the blower motor housing. If you look under the housing you will find three screws. Mine were silver.
1. I unplugged the blower motor power connector.
2. I found some additional electrical wires under the blower motor attached by some sticky tape. Remove the sticky tape and these wires have enough give that they will not be a problem.
3. I used a short wide flat headed screw driver and unscrewed each of the three silver screws.
4. The blower motor will now lower out of its housing and you can remove it with ease!
5. I used some compressed air to clean out any possible issues as a just in case.
6. New blower motor can be slipped in with ease and screwed back in.
7. Reverse you steps and now you've got a new working blower motor.

As a side note, its the first time in a while that my A/C has given me chills so I'm very happy!
***BONUS*** I'm giving props to ROCKAUTO.com I found the blower motor there, ordered it and did standard shipping. Expecting 5-8 days especially since I ordered on a Wednesday. Well they got it here on FRIDAY, basically over night shipping for standard rate.

Next improvement, performance brakes.

Awesome news. Looks like the blower is pretty cheap from Rockauto too. Thanks for the write-up.

The Infinity is complicated and expensive to service. On my old Buick I open the hood, snapped off a plastic cover near the window and removed the filter. On my Honda I opened the glove compartment, pushed two tabs in, removed the glove box and replaced the filter. This cost me less than $15 for each car. Just shows you that the cost of maintenance is somewhat related to the cost of the car.
PS BMW and Mercedes take the cake on complexity and service costs.

Ya fixed it. Well done! Glad it was so simple. Thanks for the awesome write-up!

Sad how the dealer was so far off base, but throwing your money at the problem by replacing perfectly good parts.

Good work. Will add the write-up to the FAQ thread.