2004 VW Golf, smelling fumes. The fumes come from the vents. The smell is NOT there when I have the heat, AC or circulation on. I'm confused because I do not hear anything different and would assume it would be a muffler leak. Please have good news! A single mother in school needs it! Thanks in advance!

I emphasize with you on this problem. If you are smelling fumes you are inhaling car "exhaust" which is extremely dangerous as you know. I have a 1999 Passat that had a "fume" issue that baffled me for over a year. Your description of the conditions that you smell the fumes may not be complete enough for me to definitively say what your problem is but I will tell you what I experienced and discovered on my car. I only smelled the fumes when my heat or AC was on and the car was NOT moving forward. Also, if the AC recirculate button was on I didn't smell the problem as bad. So, what I found was that the car's emission control piping was leaking the exhaust fumes that bypass the pistons and go into the crankcase. These fumes are normally piped back into the intake manifold to be re-burned to reduce emissions. With a completed disintegrated rubber emissions pipe coming off the engine block, the fumes entered into the engine compartment which is sealed from the interior of the car. So, how did the fumes get in my car? Well, when waiting at a red light and with the heat or AC on (no recirculate) the fumes would fill the engine compartment and overflow out the wheel wells and wrap over the hood to the intake vents (near the wiper blades) of the car's interior air system. If the recirculate button is pressed with the AC on, the car's interior air (no exterior air) is recirculated inside the car to cool it faster and I didn't smell the fumes as bad. Also on windy days the fumes didn't get a chance to wrap over the hood and get into the intake vents. Because of the unique conditions that had to occur in order to smell or not smell the fumes it was a difficult problem to solve. By the way, the disintegrated rubber pipe was almost impossible to see and there is no real reference material to read that describes the location and depiction of the emissions plumbing. I hope this helps you!