So basically after I installed the HCU and been using the A/C and recirculation mode, the air from the HVAC is starting to smell like ****, and the air freshener aint helping either. I have an OCD issue when it comes to cleanliness of vehicles, so all the cars are cleaned every week. However, I am scratching my head on where this issue could possibly be coming from. I am pretty sure that my exhaust ain't leaking nor my fuel line and pump. The smell I'm getting is somewhere around the lines of CO2 or CO... I just can't tell.