2011 mcs. Turned the a.c. pump on today for the firstime this year. When it's on it and stopped there is a vibration than can be heard. No weird noises other than that you can hear the vibration. The feeling and noise goes away once you turn off the a.c. i was going to check to see if it was low on freon but my question before I check could that cause the pump to have a vibration or is it just normal? I don't remember if I felt/heard it last season.

 

How many miles on your ride? Auto or manual? Where do you hear/feel the vibration? I picked up a 2013 Justa Convertible auto for my wife with 22k on the clock last August. It had an annoying vibration throughout the car (especially the steering wheel/dash) when put into gear, especially with the A/C on. Granted, we are talking S versus non-S, but with her Justa, I replaced the spark plugs, and about 80% of the vibration went away. Hers is completely stock, and that is the ONLY thing I have done to it (besides a couple oil and filter changes) since purchase 8 months and 11k miles ago. I just asked her, and she says that the vibration is still gone. Just throwing that out there.

 

It's a 2011 mcs. With 56k miles and it's a auto. Only feel and hear it when car is at idle, more in gear then in park. It's not crazy bad just enough yo tell when the a.c. pump is on. I was going to change plugs (it's due anyways) so we will see if that does anything.

 

I change the plugs in my 2011 MCS every 25k, and really feel a difference. I hope it's that simple for you. Keep us posted, please.