No heat on passenger or rear of vehicle, warm air on driver side
 

I have been dealing with the same issue in my 2011 Dodge Journey and I am hoping to get an answer once and for all. I only have warm air coming out of the driver side vent, all others are cool. The vehicle is running fine otherwise. I have had the thermostat checked and replaced, the coolant system flushed, the heater cores replaced, the actuator doors checked and replaced. Each time, the heat comes back for a short period of time (longest being about two months). I am getting ready to drop another grand to have the dash ripped out, again, with potentially no permanent fix to the issue. I have read that this is a very common, and frustrating issue with this particular model. Has anyone come up with an actual solution to this?

Yes, I have and am still having the issue, the mechanic said he would have to remove the dash - and he suspects it's the little motors which open and close the hearing portals. The issue is on the right side just like yours. I dread taking it to the dealer since they disappointed me on many issues before;
1. The front rotors started making noise after 18 months after purchasing it new at the dealer
2. The front brakes wore out within 25000 Km, the pads were so tight that when I parked the car on a hill I could leave it in neutral and it didn't move.
3. The front rotors wore out within the first year because they were vibrating when I applied the brakes
4. The transmission doesn't down-shift when going up hill, people behind me just honk and give me the finger.
Now I am facing the horn which starts honking irritably anytime it wants
I am also experiencing overnight discharging of the battery and when I attempt to start the car it just clicks but no start, I look under the hood and all I hear is random clicking from the fuse box under the hood. I tried to track down which relay is causing it but it's so random that it's impossible to determine.
I'll never go to the dealer again and I will not purchase a vehicle from Chrysler in the future.
For the itemized four issues, I told the service manager at the dealer and he said nothing was wrong.

The actuators get stuck sometimes. I try to cycle the selections about once per week to make sure they’re still moving. Usually if you tap on the actuator ehile cycling the selector, it’ll work itself free. Remove the glove box. There are 2 white actuators on the left side of where the glovebox was. The top one is for which vent the air blows out of, the lower one is for passenger side temperature. Tap on that / hit it with a screwdriver while cycling the temperature hot wait 2 seconds while hitting it, move to cold wait 2 seconds while hitting it. Keep doing this until it works. If that doesn’t work, they’re about $26 at Advance Auto, 3 screws and 1 electrical connection.

Did anybody find a real fix for this? My 2010 journey has hot on drivers side, cool on passenger side. New heater core, both tubes very hot, all 3 actuators seem to move when turning respective heat knobs.