YUCK! We had a rat die in our attic.... it took forever fore the smell to fade. I don’t like to think how long it would take for this odor to fade.
Imagine coming back from vacation to find out that a possum had crawled up into the hvac system and shorted out the heater coils. He got electrocuted and since the system was out in the hot Florida sun for a few days you can’t imagine how bad a maggot infested possum, dripping over the coils, could smell. I’m getting sick thinking about that smell.
Years ago, our first house was an old Victorian that had been rebuilt over the years. The front bedroom had been a porch and did not have hot-water radiators. Instead, someone had installed forced hot air off the furnace manifold.
Well, we had a lot of cats. Cats like to find and play with and then kill mice. One mouse fell through the hot air register and down into the furnace manifold. So every time the heat came on, the bedroom smelled like hot, dead mouse. In desperation, I poured some Aqua Velva down the register. Big mistake. Then, every time the heat came on we could smell dead mouse wearing Aqua Velva, which was infinitely worse. Took months for the stink to stop.
Here in Florida we have these little green tree frogs that get inside everything. And sometimes they can’t get back out!
Had one die in my car’s AC vent...................horrid smell for a long time!....................