Whenever I turn on the ac/heat or heating system. I can smell diesel coming through the vents. Any suggestions.

 

I would check around the engine compartment for any fuel leaks in either the hard lines, returns, or ip delivery valve area. Diesel fuel leaks can be hard to find, but if you have one you can sure smell it even from the outside of the car. Last year I had a couple of delivery valve seal leaks, and the area of the leak was just damp, not even showing any evidence of a leak, but after cleaning off the area with carb cleaner, and having the engine at idle, I could just about see where the fuel was coming from, but you could smell it from 3 feet away. Good luck

 

Thanks. I'll take a look.