rolling18

after MUCH MUCH searching on here I was unable to find what is wrong.

I have a very very bad smell that comes MOSTLY through the defrost vents
like **** smell. i tried squirting things down the vent but no good.

it does NOT smell on other settings regardless if A/C is on or off. I Think it smells like stale animal **** as the previous owner has an animal. unknown history.

i think im going to have to take the dash apart until i can get to the HVAC parts/ ducting and smell around

can someone tell me how to go about this???
all i could find was A/C door and moisture/ mildew problems but this is not that as it only happend in 1 or 2 settings

thanks!!

Big Red 97'

When i had my 95' mine blew a horrible smell only in vent mode didnt matter wether it was heat or a/c. Defrost vents and all were fine it was only the normal vents. Mine smelled like mildew but it was strong, i couldnt even sit in the truck with the vents on. I never figured mine out though, i just drove with the windows down. Could be mildew or moisture only in the defrost vents, its possible to just be in the vents, not the whole system.

Vance

rolling18

thats what im looking for help to do.. clean the ducting or wherever the stank is comming from..

On a side note: i think i found the AC evap. drain tube.. it stick straigh out about half way down the firewall... is it "normal" for it to be blowing cooled air out into the engine bay?

Big Red 97'

I have never heard of that, that seems odd. Im not the best help on these trucks especially 3rd gens, i know a little bit but im still learning. But i have never heard of a truck blowing cold air out into the engine bay. Hopefully someone else will chime in that is a little more knowledgeable.

HotRodTodd

Well, here is one I am working on right now.
This thing stunk like you would not beleive. I hope you don't have to go through all this.

HotRodTodd

This is what it should look like

rolling18

what is that called?
and how did you get it out??

mine could be like that.. i have 170K.. and the truck was "well used"

HotRodTodd

That my friend is the evaporator from the HVAC box under and behind the dash.
You have to remove the entire dash to get it out, and several things under the hood too. I swear I will never do another one again, it is a nitemare.

rolling18

YUCK doesnt sound like anything ill be dooing.. luckily the AC is still ice cold!!
and i dont notice the smell when its on. only when air is flowing throught the upper dash vents!! uhh!

pullin hard

just saw your sig, wet dog smell, thats funny
my friend works at a dealer, chevy dealer, and he said they have stuff they spray into the vents and such to eat away the mildew and mold. its exspensive, but might be something you want to look into instead of ripping things apart. i tried one time to do my evap and i ended up wasting about 8 hrs of my time, let the dealer do it, it too was very exspensive, and they broke my mod door and my dash, that how they do it so fast. anyway, i wouldn't let them do it again even though the damage is al ready done. my dash rattles just like my injectors do.

HotRodTodd

Yeah that dash will rattle like heck if you don't replace all the foam strips around the vents and fire wall.
I have done several of them and take my time and replace all the insulators and foam pieces. No rattles, or at least none from my work. It is a real PITA, to do them the right way for sure.

pullin hard

and i am sure the 20 screws that some how got miss placed doesn't help either!!!

rolling18

welp, i just BROKE my a/c system!!!

while following another A/C thread here, about how to install and use BG frigi-clean i didnt drill the hole for the injection port in the exact same place.

so ofcourse i drilled a hole in the evaporator core!! witch was touching the inside of the plastic case ..

4 minutes of Pshhhhh.. i have no a/c gasses anymore..
so now it look like i get to replace the evap

Jeff in TD

Ouch.

This thread might be helpful.

https://www.dieseltruckresource.com/...d.php?t=210483

Somewhere there is a thread about how to remove the dash...

1985cucv

could be a dead animal i had a mouse nest in my 85 it sucked!