The blend door is stuck. Either a vacuum line behind the A/C controls is loose/broken or a pen/coin or something went down the upper vent and lodged in the blend door and wedged it open......
Nah, go to a mechanic shop, they will laugh at you and stick a pen camera that they use for cylinders and what not down the vent, snap on the light and look for you- either that of the vac line right next to the passengers side firewall cracked or melted-
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