Dodge Repair: A/C question 2003 intrepid -ES

Question
a chemical type odor is randomly coming from my air conditioner vents.  i have 2003 dodge intrepid ES. It started about 3 months ago and has gotten more frequently.  it's a nauseating and sweet smell. no film on on wind shield.

Answer
Hi Faye,
Try smelling the fluid in the cooling system expansion bottle in the engine compartment to see if that has the same smell. I am not certain whether the AC systems's R-134 refrigerant would have that smell or not. My thought is that there is a cooling system leak in the heater core rather than an air conditioning leak. Have you noticed that the coolant in the expansion bottle has been disappearing? If so that would support my theory. Also if there is moisture on the carpeting under the dash that would be the leaked coolant.
If the AC stopped working then that would lean toward a refrigerant leak. You could ask at an AC shop for them to smell the odor and give you an opinion if you can't tell.
If that cooling system fluid turns out to be the odor, you could attempt to seal the leak with a chemical that you would put into the expansion bottle which when then drawn into the cooling system has the ability to plug up small leaks. One of the better brands is called "Bar's Leak". You would dilute it with water and add it gradually to replace the lost coolant until the leak is sealed. It is available at auto parts stores.
Otherwise unless the leak is at an accessible disconnector which simply needs to be tightened, for either the refrigerant or the coolant fluid, it means a removal of the entire HVAC housing under the dash to replace the leaky heater core or AC expansion part, and that is a big job which should be avoided if possible.
Let me know what you conclude and whether I can be of further help.
Please read the PS (below) and respond to it.
Thanks,
Roland