Noticed smoke coming out from the a/c vents and along side the front windshield, fogging up the window. The service engine light is on, but that has been on for sometime, then it went off last week, and is back on again. Auto Zone's machine read something with the EGR. I own a '99 Ford Expedition. Could it have anything to do with the heater core? I am a single parent raising my granddaughter. Any assistance would be appreciated.

Hi,
First off, God bless you for stepping up for that baby!
OK about the vehicle... Generally when a heater core goes bad, the symptoms of a white smoke occur from the vents. Another symptom is a sweet smell from the antifreeze, possibly dampness on the passenger carpet, dryness in the back of your throat... ha.
Sorry... heater cores aint cheap... mostly labor entensive. You could continue to drive trhe vehicle until you are ready for repair or whatever you decide to do. You'll just have to put up with the symptoms till you do, and you won't have much luck defrosting.
The engine code shouldn't pick this up... that's a different animal.
Hope this helps... Good luck!