I have a 2004 two door 2wd Blazer. I have a bad smell coming from the vents when the heat is on at start up. It seems to clear up after a few mins. I am not noticing any smoke or leaks from the heater area. It is a chemical or exhaust type smell. Any Ideas?........1SG

 

Smell like antifreeze? I just finished fixing that problem, I had no leaks but that awful smell, after the truck heated up it went away. But my problem was a bad heater core.
Took me about 8 hours to do. Its not that bad just takes alot of time to do.

These trucks are prone to bad heater cores so im sure that it...good luck

 

I just replaced mine also. Allow yourself plenty of time, you want to get it right the first time. Read Adam Crosier's write up with pictures, it is a big help.

 

I did a pressure test and it is holding good pressure. It seems to only happen in the morning and I guess it could be exhaust or even freon? Any other ideas before I take it to a mechanic friend?........1SG

 

there can be a build up of crud under the plastic cowl at the base of the winsheild

the drain for the a/c can also plug and cause mold

 

would that cause the bad smell only at start up?........1SG

 

on start up you are dealing with stagnate air

 

Have you been losing coolant?

 

My windows will fog up after my engine has been running for a while,Im not loosing any coolant and the heat will get so hot you have shut it off after about 5-10 minutes.The fogged up window goes away also but I have no smell of anykind when it happens.

 

Could be stagnant water in the housing due to a plugged drain pipe.The drain is on the outside of the firewall and will look like a black rubber hose with a duckbill end.Cleared mine and water drained out for about 5 minutes.Strangely,the swishing sound went away while making turns too. decided to clear all the body drains too,there are some at the rear that were holding a lot of water too.