Hello. I can think in two possibilities here. The first one is that the heater mixing door can still be half open, allowing hot air to enter partially to one side, in this case the left side, this hot air is been pushed out by the blower. The reason for taking the route to the left is precisely that is half open, such aperture been more near to the left tunnel than the right one. You can make an easy test to see if the heater has something to do with the problem. There are two hoses that enter the firewall from the engine area to the inside of the dash board, usually both run together, they just flow hot water to the heater inside the dash board to warm the air. If you press them both with pressure pliers, from the engine side, not allowing the hot water to flow, there will be no heat inside the dash board. If in a couple of minutes cold air flow to the left side, the mixing door is half opened.
Now the second possibility, a little more far away, but possible. The evaporator, which is the part that gets cold, sometimes acquire too much dirt, considering the air travels through it, including dust that becomes smudge because the evaporator is not only cold but also wet. If the evaporator gets too much dirt in only one side, such side will allow the air to flow but will not get cold. Dirt impregnated on it does not allow this area to get cold. So, if this is the area that flow the air to the left, it can flow warm air in that area, and cold air to the right side. This possibility is compatible with an evaporator with 71000 miles on it. If this is your case, the evaporator must be replaced.
The air conditioning system of a car is not user serviceable, you must take the car to a refrigeration technician, not a general mechanic. I can not believe this mechanic took the dash off because if he would, all the tunnels would have come off also, together with the dash board. If the tunnels are out with the dash board, then how did he entered hands inside the tunnels? What I mean is that may be he is not a good mechanic. If he would be, he would not be stumped, he would have diagnosed precisely your car and not tell you simply, I don't know what happens.
It is not easy to diagnose from here, again, an air conditioning mechanic is the most recommended in your case. Good luck!!
Last edited by Ignorant : 07-17-2008 at 09:26 PM.
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