I have a 1999 dodge ram 3500 van 15 pass. and the rear ac vents are not blowing. What is the first thing I need to look for. They use to blow hot air, but now they dont blow at all. The front vent are blowing, but when I am in an incline or accelerated speed, the defroster vents and floor vents would blow and than switch back to front vents. Right now the most important is to get the back vents back blowing. Please help!

 

On the rear check that the fan motor has power going to it, if so then the fan most likely is bad. If no power check the fuse.

Front check for a bad one way vacuum valve on the passenger side manifold. Also check the vacuum lines under the hood for cracks. There is a vacuum ball reservoir on behind the right head lamp assembly, check it as well.

 

The fan does have power going to it, as it was straight wired, which has a toggle switch. It was like this when I purchased the van, I dont know why it was straight wired. Or is there a second fan motor for the rear vents?

 

Okay, need some more help with the vacuum hoses! I have tried to locate the vacuum hoses that is connected to the back vents with no luck. It seems that all of theses lines look alike. Can anyone tell me specifically where these lines will be, and I also cant find the one way vacuum valve. This a lot more difficult than I thought!

 

Does the rear unit work on vacuum or electronic for actuation?

If it's electronic like the 1994+ rear HVAC systems, then this controls the rear vents.



You will need to unplug the connector and unscrew the three screws that mount it on.



If this is the part that moves the vent doors, then you will need to take it to Advance Auto. Just make sure you order the correct one. There are about 32 different types of this actuator.

As for the motor being straight wired in, if it's working, added an in-line fuse. Walmart sells the Bussman for a few dollars in the automotive section. If the motor is not working, the brushes are fried in the motor and you will need to replace it.

 

Not sure if its electric or vacuum. I know the front is vacuum. Where do I need to look for this part?

 

It's very seldom that the rear unit is vacuum because of the long distance to the rear of the van. You will need to look at the rear unit for an actuator similar to the one I've posted.

If the rear unit is vacuum, you will need to look for something like this ...



OR like this ...

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Or try this HOW TO fix general page ...

http://www.fixya.com/cars/t4243105-rear_c_dose_not