Why there's sour smell coming out of my ac vents
Sounds like a dead mouse.
or mold, that grows on the evaporator. There are ways to clean it off.
Remove any debris around the cowl (vent intake) ie, dead leaves, pine needles, etc.. Run the vent on high for around 15 minutes without the AC on to help dry out the evaporator coil. If the vehicle is equipped with a cabin filter, replace with new. Those are some easy things to do without too much work.
..as stated above check cabin filter, behind glove box, easy to do
Seems to be a common problem with Toyota vehicles. Several Factory Service Bulletins have been issued regarding this issue. Try a Google ...of your Make...Model...Year. Some suggest the Evaporator and AC Amplifier needs replacing. Suggest you do the easiest and cheapest repair first.
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