I'm getting a pretty strong Chemical scent from the vents more when on recycle mode rather that outside vent. Really bad when A/C is on. New filter perhaps or is it a A/C gas leak?

What has happened is mold has grown in your vents from the condensation of the AC. I replaced my filter and sprayed lysol the filter housing while running the fan full blast, it seemed to work.
Before you turn your truck off, turn the AC off and run the vents on full blast to dry them out some.

Not to say you don't have a leak but if you did, I think the AC would die pretty quickly. As DURYMCGEE said, I had new life forms spanning in my vents. I got a product from the dealer to do the same thing. It comes in a pump bottle and has a little proceedure on the lable, but basicly - what he said. As I remember you're suppose to remove the filters and turn the fan on while sparying. Let it sit for a bit and repeat. It is suppose to kill mold etc inside the duct and exchanger. It doesn't smell like lysol but I don't know what it is. Says you can use on other stuff like carpets also.........

Not to say you don't have a leak but if you did, I think the AC would die pretty quickly. As DURYMCGEE said, I had new life forms spanning in my vents. I got a product from the dealer to do the same thing. It comes in a pump bottle and has a little proceedure on the lable, but basicly - what he said. As I remember you're suppose to remove the filters and turn the fan on while sparying. Let it sit for a bit and repeat. It is suppose to kill mold etc inside the duct and exchanger. It doesn't smell like lysol but I don't know what it is. Says you can use on other stuff like carpets also.........
I just had my 3500 in for service and I asked about the odor coming from my A/C (the odor smelled like lockerroom -:t ), anyways, I had them replace the cabin filters and they sprayed some kind of stuff in there and it has been great so far...over a month, and it is hot & humid here in So. Indiana. Also, just like mentioned above I push the A/C button and the recirc. button to the off position about a minute prior to stopping (blower on 3) to prevent this from happening again. I also think that if you had an A/C leak after a day or two you would notice a definite lack of performance of the A/C....like not working.
JP
JP

From my past experience with an evaporator leak, the 134a stuff kind of had a burning plastic smell inside the cab with the air running. The nasty dirty feet stink seems to be a common GM truck issue.

Just started noticing the same thing in my truck. Just a little nasy coming out right when I crank a/c. No filter on mine but I will try the Lysol trick. "Ozium" works good on smells also so I may try that too.

Ozium might work, but only if it will kill mold. That's what is making the smell.

Bleach water mixture poured down the cowl where the air enters the evaporator will take care of the problem.

I have to do this once a year in good old humid Houston!

Bleach water mixture poured down the cowl where the air enters the evaporator will take care of the problem.

I have to do this once a year in good old humid Houston!

:exactly: U beat me to the same response.

Have you guys checked your A/C water drain on the pass side of the truck? You may have a partially clogged drain tube.

I'm amazed the amount of H2O that drains from the A/C on my truck.
The A/C is doing its job well.

I noticed the smell too. I thought it kinda smelled like cat piss.-:t

Have you guys checked your A/C water drain on the pass side of the truck? You may have a partially clogged drain tube.

I'm amazed the amount of H2O that drains from the A/C on my truck.
The A/C is doing its job well.

I gotta check on mine... is it really noticeable when you crawl under there... I occasionally get the smell, and I noticed the other day when I moved my truck (after sitting over night) a fresh puddle of water like it suppenly decided to drain when I moved it.

Where are the filters in the cab, noticing the odor for the past few weeks myself.