Cant get ac or jeat to come out vents.was only coming i out defrost not anymore

Hello, You likely have lost a mode door. Mode doors and blend doors are inside the HVAC box, behind the dashboard, and serve to change airflow to different directions and temperatures, depending on what you have selected. There will be at least 3, and up to 5 blend doors and mode doors combined. Of course, you could have an issue with the circuit, but either way, this vehicle needs diagnostic testing to find the culprit. Let me know any questions you have, and here is a link if you would like shop recommendations: http://repairpal.com/mercury-within-10-miles-of-sand-springs-oklahoma-74063