Have you tried reading this one
What's That Smell??

the article is very simple but could really simply help also.

 

I was going to reply about checking the AC system. Does the 2004 Impala have a cabin filter? I think my 2001 had one and it was located underneath the plastic cowl cover on the passenger side of the car. Do you think a plugged filter could cause it? Also does the blower work on all speeds? if not could indicate a problem with the motor or the dropping resistors.

 

I haven't test the AC yet, but since its warming up now I'll give that a try. The blower does work on all levels. I'll also have to check the cabin filter, and if it even has one.

 

Sorry its been awhile since I replied. The AC works good, but haven't had it running for extended periods of time. Still 30 degrees, here.

Checked the cabin filter, and that looked good. So I am running out of ideas.

Today on the way home I put the temp to all the way cool, and didn't notice any chemical like smell coming in. Put the temp to hot and then I could smell it again. This was with the fan off.

When moving the temp gauge to hot or cold, How does that mechanically change with the heater core? Does it shift the vents to not be on the core?

 

There is usually 1 blend door... so you can have a mix to set the right temp.

I haven't re-read this post - but is this your car originally or used? Has there been any work related to the heat??

So was the ac circulating or where you pulling in fresh air from outside?

 

We bought it used from a car dealership. Its been an excellent car, but the miles are getting high.

I can't remember if I had it recirculating or pulling in fresh air...I'll have to test that out again and take note.

Is there a way to stop all air coming in? Even when the fan is set to off air still comes in.

 

I took my car to a mechanic today, and of course he couldn't smell the smell. But he did a diagnostic test on the codes and he found the thermostat was bad(I already knew that) and the MAP sensor code showed up on the scan.

Could that be something that might cause the issue? I'm Not too familiar with it.

Too much fuel getting in, running rich.

 

It's the windshield wiper fluid your using. Since you live in a freezing environment you have to use a anti-freezing type windshield wiper fluid so it won't freeze in the reservoir.
I had the same problem with my '07. Flush the reservoir with water and flush the vents in front of the windshield with water to try and flush the old fluid. Be careful when buying windshield wiper fluid.

 

Did you ever solve the problem?
I realize this is a very old thread, but I've just run into the same problem.