I've had my MC since mid-January and now that I've started using the A/C, I've been hearing a noise while the A/C is on and my foot is on the brake. What I'm hearing is a faint knocking sound; sometimes I think I can feel it; sounds and feels like it's coming from under the car. I'm wondering if it might have something to do with metal contracting because the sound reminds me of the knocking noises the car makes after I turn it off. I'm not worried that anything is wrong, I'm just curious as to what it is. Anyone?

 

Not sure I understand what you are describing.

Is the noise regular (i.e. rhythmic) or intermittent? ("metal contracting" is not rhythmic!)

Braking from speed... or foot on break at stop/in neutral?

Does the sound disappear right away if you turn off the AC?

 

Does the sound completely go away if you switch the air off?

 

Do you have a manual or automatic MINI?

 

I have a CVT. The sound does sound rhythmic. In fact, my husband guessed it might be condensation dripping on metal from the air conditioner. But I don't think so, because as I said, I can "feel" it while my foot is one the brake. It happens when I'm stopped at a light; the car is still in Drive, my foot is on the brake. And there it goes....tap...tap....tap (maybe 10 or 15 seconds between taps). I always have the A/C on now and I don't remember ever hearing it without the air on. And it doesn't always happen either!!! So, the sound is rhythmic when it happens, but it happens intermittently . And it could be that it's not happening those times because I don't have the A/C on....I'll have to be more diligent to see if that's the case. Any guesses?

 

Is it the drippng of the water from the A/C? And when it hits the pavement it hits with the force of lead.

 

Hmmm, well it could be the A/C compressor starting to go bad, but that is just a guess. Take it to the dealer and have them test the A/C system just to make sure nothing is going wrong with it.

 

I'm going in for an interim oil change soon and I'll ask them to check it out. Thanks for your guesses, everyone! :smile:

 

Did you ever find out what this was? I ask because I noticed a similar issue on my new MCSa the other day. But I have only heard it on one occasion. The dropping noise sounded like it was hitting metal as well.

 

No, I haven't been in for my interim oil change yet. But I did notice that it happens with the A/C off as well, so it has nothing to do with the air conditioning. And it is very intermittent as to when it happens. I'm not worried about it, I just chalk it up to unexplained car noises.

 

do you have aftermarket exhaust...mine used to rattle from the extra load on the motor at idle with the ac on. I had more hangers welded on and it fixed it.

 

No, I don't have any aftermarket add ons. Maybe mdsbrain does?

 

Nope.:smile: I haven't heard it but once so I wonder if its some weird "engine break-in" noise I've only got about 250 miles on the tach (I need to drive it more).

 

I called my MINI advisor in service and he said its fluid dripping from the condesor when the A/C is on. The only thing I didn't tell him is, I only hear on a stop after driving the car hard and fast

 

I made an appointment for my interim oil change for next week. Our dealer is 30 miles away so if we hear it on the way, I'll ask service about it. Otherwise, oh well.