2000 F150 4.6L 2WD suicide doors. At startup I smell a mild yet distinct wiff of cider vinegar. this happen only occasionally (12 times in the last 3 years) and is always short lived (<10 seconds), no mater the weather or temperature but the blower must be ON when started. Never accompanied by fogging.
I have heard a lot about the sweet smell accompanying a leaky heater core, but I am not sure what that smell is like. I would not call this smell sweet. I did mixed antifreeze (Sierra) with water and brought it to a boil. the smell was not vinegary nor, what I would call sweet. No lose in coolant no sign of coolant under dash.
Anyone have an idea to the cause of the smell?

Thanks , Russ

 

They sprayed Vinegar and water mixture into the ducts. Why?? I would guess that the previous owner was a smoker. Vinegar and water helps to get rid of the cigarette smell....
Just my $.02

 

A/C makes a musty smell when you park the truck after long operations, try turning the a/c off a bit before you get home and leave the windows down or cracked

 

Even worse if you live in a humid climate. Just shut the a/c early while leaving the vent on and make sure you are pulling in outside air not recirculating, this should help dry it out and keep it from smelling.