Somehow a critter, likely a field mouse, has crawled into my '77 cab ..... and has died there. It's small, but it's for sure there somewhere. On the driver side kick panel vent there is a sliding door and a screen of sorts as I recall. My truck originally had heater and defrost .... no dash vents as was no AC On the passenger side where the AC / vent draws air through the kick panel hole, I don't think there is a screen. I recall several years ago removing the accordion like rubber to clean the cowl vent bowl that has a hole pointed towards the ground. I know I removed the sliding door, etc on the driver side too. My truck still has an evaporator blocking a critter from the rest of the AC ducting, but a critter might get into the cab that way. I don't see much getting through the cowl vent slots in front of the windshield, but a mouse might somehow get up off the ground and up to the cowl vent "well" that has a fairly nice size drain hole at the rear corner, near the lower door hinge.

I can't think of any other places a mouse might get in, but am open to suggestions.

Update:
Well, went out to try to sniff it out, can't smell it now. I know odor was there, Wife smelled it too earlier.

 

I had a mouse nest in that driver side kick panel vent. Most likey, IMO, that might be one area where it came in. I found mouse evidence in the interior roof channels where the headliner trim screws in. My guess is that they squeeze up the A pillars.

 

I contend with field mice too. My defense system is peppermint spray and bait blocks (Tom Cat brand). Seems to be working for me as I haven't had a mouse in any of my vehicles for awhile now. I cut up the bait blocks and place them strategically around the engine compartment where they will easily find it. Last resort....you might have to trap it to get rid of it. I hate rodents...

 

Been using a few different items to keep mice and Cats out of my 1995 F150 that's parked for extended periods under an awning with a car cover on it. Had a long haired Cat last Fall 2025 making the engine bay it's home. My neighbor told me he uses three small yogurt containers with Cayenne pepper flakes in them. So I did the same and got woke up the night I put them in the engine bay with a Cat sneezing. Haven't had another CAT inside the engine bay since, but I replace the Cayenne pepper flakes every 2 or 3 months as they get clumpy from humidity and lose their pungent smell. Put a small yogurt container inside the cab with three small sacks of lavender, have not had mice or any signs of them inside the cab or glove box. Note, the lavender is too powerful, will give me a headache, so I remover it when I drive the truck and put it back inside when I park it.

The 77 F150 is stowed inside a tightly sealed garage (at least I think it is) and haven't had rodent problems inside the garage or truck.