My 2007 VW Jetta just started making a noise.

is the RPM gauge actually reving up ? it is normal for the rpm's to decrease slightly when the AC is engaged and increase when disengaged, this will also engage your electric cooling fan/fans this will effect the rpm's as well. The AC compressor will disengage and re-engage when the AC is on if your fan belt is worn it may make a sound like you described. The slight vibration you feel is most likely the compressor engaging after is cycles threw the compression stage. If you can have your hood open with the AC on watch the compressor when it cycles threw on/off you should be more able to pin point the noise your hearing.

Hi Jon, Thanks for the response. the RPM doesn't actually move. It just sounds like it is revving up. Not sure what the heck is going on with it, but its stressing me out. I haven't had any issues with this car and I sure do not want to start now! I don't know where the "compressor" is located. Sorry, I'm a girl that doesn't know much about cars, hence why I'm online asking the questions! :) Sorry, Thank you.

Also, the engine block was shaking way more than normal and we thought it may be the plugs or have to do w/ the fuel air sensor(?) We disconnected the battery for about a day to reset comp as some forum stated it could fix the issue. While the car is running somewhat better, it still seem to have a tick that wasn’t that noticeable before. and still sounds like it is revving up and then down when the A/C unit is on, however the RPM's do not move. Thank you!

sounds like your hearing the electric cooling fan or fans (sometimes 2) some have a mufti-speed function that will speed up randomly and slow down this would make a sound similar to what u described. Wouldn't hurt to do a tune up if you have 80,000kms or 50,000 miles since your last tune up. For peace of mind just pull into a vdub dealer and ask the service manager if he could have a quick listen and then get the car to make the noise u hear while he is there right away he will know, tuff to diagnose over MB's good luck

Thanks for your help Jon!!

let me know once you figure out what it is I'm curious to know what the noise is. Cheers!

I am having the same issue however, it only makes the sound when I am driving. The a/c does not have to be on and the rpm's are normal. All my gages are normal as well.

Yep having same problem and its a 2007 im think its the thermostat

There are two cooling fans, one for the cooling system, the other for the A/C. Try looking at the cooling fan when the engine is warmed up. It will cycle on and off to help maintain the engine temperature. The fan should be running very smoothly. The same goes for the other fan. Check the other fan by turning on the A/C. It will also cycle on and off as the pressure in the A/C system fluctuates.The fan should also be running smoothly.

The noise complaint only heard while driving is probably not related to the original poster's complaint. He may have a bad wheel bearing. The engine cooling fans can go bad in the Jetta, causing the noise and vibration. There will be fault codes present in the system to indicate whether one or both coolant fans are faulty.