What do I need to doin if the rear a/c top vents stop blowing the air out?

could be a number of things . such as switch stuck air flapper or fan motor.

If this means that you have no rear air at all, the problem is a cheap resistor that you can replace. Ask a parts house to find the part and show you where it is located. You can do it and it's a cheap, easy fix. If some air is blowing out of other rear vents, then the problem may be a fan and not just the resistor. Air can be blowing out of the front vents like crazy and the problem with the back can be as I described sense front and back have separate resistors.

No good answer here.... A Terazza has a different type of system and this problem is very common for this model.
Any answers at all for the Terazza or Uplander??
My Uplander has the same issue...No Blocked vents. Just no air out top vents. Bottom discharge only.

I had the AC problem too, and they said there was a hole in the hose. They fixed it and now it comes out of the vents as it suppose too, but when I first accelerate to go up a hill, it stops blowing out of the dash vents. Once I have stopped going up the hill, the air starts blowing out again. Weird.

its the blend door behind the glove box. I had the same problem

no but there is a expansion valve u will need to replace

Hope I was avle to help, glad you up and going.

the resister block needs changing... oddly enough i'm unsure of what fan you are saying is not working.... if it's the front.. the resister block is located on the duct work under the dash for the air... near the fan... you will see a connector going into the side of the duct work. two screws and the block comes out... should be fairly obvious for the rear one but it will be near the fan.

Hello according the the manual, the back vent are to blew cold air only..the fronts vents are suppose to the entire car...

If you have the heater control up front on the floor or on defrost you should check that the heat is not blowing from under the d/p seats. If you move the heater control to dash you should have it coming out the top vents.

You could be having a coolant problem and need to check that first, If coolant level is normal you might have a thermostat going out. Both will cause your heat not to warm up at normal speed. If you need any thing let me know.