Ford Explorer air conditioning problem

Hello everyone in the forum, I have a Fordie Bauer truck, year 2006, for two months, when accelerating the truck, the air -conditioning exit of the front grilles changed to the defense, when stopping, the air began to leave the air again through the front grilles. He took it to the mechanic and told me that the problem came from a leak in the hoses of heating, they were replaced and the problem persists, no mechanic occurs with evil.
Any of you to have a similar experience? Does anyone know what is happening? I would thank you very much ...
Thank you!

Hello partner, the problem I think you have it in the air box where the 2 radiators one of heating and the other of the air conditioning that also crosses the springboard selects where the air comes out and if it comes out cold or hot according to selections with the roulettes ......
You have released a spring