I recently purchased a 99 Blazer. I was having trouble getting it started but I just needed to change the cap, rotor, plugs, and wires.

I tried testing out the air conditioning and at first a bunch of dust flew out of the vents. Then after about 5 minutes of running the air wasn't getting cold so I cut it off and figured I need to have the AC recharged or something.

Anyway, after about 10 minutes I get ridiculously dizzy, sleepy, and felt like taking a nap. Thankfully I was very close to my house and I stayed outside and inhaled fresh air, while flushing my system with water. Needless to say after about two hours my symptoms cleared up and I knew it was Carbon Monoxide.

So my question is: Is this an exhaust leak? Or is it just mold in the AC vents? The guy I bought the car from told me I need to replace an O2 sensor, and he repaired a pipe that was "busted." I do not get this feeling when the fan is off, and after that one time I have been afraid to try it again. Any advice is much appreciated.

 

Sounds like an exhaust leak to me. Can you hear any exhaust leaking around the engine bay or underneath the vehicle? I'd suggest you make sure you're working outside or in a well ventilated area and keep all the truck windows open while your checking it to make sure you don't get a buildup of carbon monoxide.

 

Very dangerous stuff. Get yourself a CO detector and put it in the cab with everything running and you outside. See if it goes off then track the leak. Your not wasting anything, everyone should have one in there house anyway. Homedepot.