I had the same problem with my '03 Limited, but then the driver's side quit working as well. After further internet investigations, I learned that it is usually the heater core, located deep under the dash. To do the work yourself would take a lot of mechanical skill, and a lot of time. I took mine to the dealership, and they gave me an estimate of $1300. The steering column and the entire dash have to be removed. I have been driving to work in Colorado all winter without a heater. Just be thankful that it still works on the driver's side.
It must be a Jeep thing because I had the same problem with my 2001 Jeep Grand Cherokee. My boyfriend picked up a heater core for about 200 dollars and put it in himself. He's no mechanic so I don't think its that hard if your willing to put a little effort into it. Plus you save about 1100 dollars!
Passenger side under the dash board. That big black box which routes all of the air to the vents has to be removed.
The Vents Are operated by vaccum.. I found a cracked vacuum line on the inner fender under the hood alondside the battery that was cracked. the vacuum line runs from the firewalll to a reserve canister located under the passenger headlight. as soon as the leak was plugged the vents were working again.
Either you need to pen your vents or there is some vent obstruction.
Does blower motor run?
I have the same problem with my 97 jeep. I'm thinking that maybe a hose going to the vents has come loose, because I can hear the fan motor running and I'm getting a small amount of air out the vents in the dashboard area.
The heater coil probably has a leak causing steam and vaporized antifreeze to be released into the vents. Is it using coolant?
It doesn't have one. There is a useless screen under the cowl on the passenger side (where the hood and windshield meet). It is supposed to keep leaves and junk out, but it doesn't. This is why the drains clog so often on these vehicles and you get smelly mold coming out of the air vents.
i believe the heater core is leaking, a small pin hole leak can generate a lot of smell.
Check behind the passenger side headlight between the headlight and battery for vacuum line leak! That is where mine was little rubber hose and it worked again
Check for vacuum leak either under the hood or under the dash Check the operation of the vacuum actuators Check the selector switch Defrost is the default setting on this system
The temperature settings on the rear vents are the same as the front vents on the same side of the vehicle. Ensure they are on heat, turned on, and are set to blow out the top (not toward the passenger's feet).
Could the heater door actuator be bad? What is the cost to replace? This Grand Prix has a dual-zone climate control and when the AC is on, the passenger side vents often change to heat when the control is still on cold.