allright here are some updates....
I went for a long drive tonight to figure out what exactly is going on. the CO detector showed normal readings through out the drive. here's what I found. the cause of the headache is the heat.. not the vents or the air from outside. with the temp to the heating level, it feels as if someone has sucked the fresh air out all together and I need to open up the windows to breathe. but when I turn the knob to cold temp everything is perfectly fine. I tried it with both on the e/c mode and also with the A/C on in both hot and cold levels. same thing. when the hot air blows through the vents it brings along headache...
I tried to smell the antifreeze but couldn't. the coolant level is perfect as well.
Here are the questions :
with the heater on, are all the vents for cold air closed or is the fresh air mixed with the heated air and then blown in through the vents ?
secondly, what's the path that the hot air takes starting from the front of the car all the way into the vents... because obviously somewhere along that path is where the problem lies...
I'll wait for everyone's replies..
thanks !

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