Random rotten egg smell through Ac vent?

[SnowDrifter]

A bad battery will have a fairly potent rotten egg smell to it too. Conveniently it's located by the inlet for the HVAC system.

I wouldn't think you'd get any exhaust smells in the cabin, especially while driving.

 

[Jody Woody]

I have a 2017 LT 4wd with 50K miles. I have the same smell. The dealer replaced the catalytic converters and it changed nothing. It almost smells like natural gas. I cant find any oil leaks. It has been to the dealer several times for this issue. Any Ideas??

 

[ivin74]

I have a 2017 LT 4wd with 50K miles. I have the same smell. The dealer replaced the catalytic converters and it changed nothing. It almost smells like natural gas. I cant find any oil leaks. It has been to the dealer several times for this issue. Any Ideas??

@Jody *****
Have your battery checked out, some batteries release weird smells when they start going out.

 

[Jody Woody]

So I found the smell but I don’t understand. The vent for the front differential comes up and attaches beside the main fuse box. 12” away from the fresh air intake of the HVAC. It has a vent cap but it does nothing but keep dirt out. I opened a new bottle of AC Delco gear oil and it is the exact smell.

 

[Jody Woody]

Yesterday I attached 6’ of vacuum hose to my diff vent hose and ran it up my a-pillar. I taped it to the top of the roof and have driven it for 2 days now. No smell at all! What’s up, why can you not smell this in other Tahoe’s?