Lately on start up I have noticed a musty smell when starting my car with the a/c on. It has been a while since I had a car do this. Last time I bought some disinfectant/deodorant that you spray into the HVAC air intake and that seemed to get rid of the problem. Before I buy some gunk to spay into the system, do any of you have any experience doing this? I don't want to spay some crap into the HVAC system causing more problems. Or is this something I need to let a qualified technician perform. I don't think the drain hose is clogged because I usually see water grips on my garage floor when returning home on the passenger side.