I'm having a problem with my front AC vents not blowing when I turn the AC on. If I turn the rear AC vents on from the front controls and the rear controls, the vents in the back will blow and blow cool air. I have had a problem before the front vents completely shut off in which the front vents would blow on settings 1-4 but the AC would shut off on the highest setting of #5. Now the vents in the front do not blow at all. Please give any suggestions that I can try before spending a fortune at a shop. I am very capable and resourceful. Thanks.