Q: Exhaust smell coming though AC

Hello. I will help you with your question about a possible exhaust leak. There are a variety of odors you could be detecting. If the A/C system is operating, there can sometimes be some pretty strong odors due to the condensation that collects in parts that are in the passenger compartment, principally your A/C "evaporator". That condensation allows mold and mildew to grow and the odor therefrom can be pretty objectionable when you are running the A/C. Hard to say if that is what you are referring to. If it is not THAT odor though but rather exhaust gases from the engine, that is serious because exhaust is part carbon monoxide. YourMechanic can determine which of these possibilities accounts for the odor and schedule the repairs. If it is an exhaust or exhaust manifold leak, I encourage you not to drive the car until it is repaired. CO is a known and well understand cause of poisoning and even at low levels is well known to damage your health (search on Internet: "effects of chronic exposure to carbon monoxide").