Auto Air Conditioning & Heater Repair: 2004 Toyota Sienna AC one side blows warm air, logic control, correct signal


Question
I recently had the dealership changed the air filter of my 2004 Sienna. After I got home, I noticed that there were a big leave and a few small pieces in the blower. I took them out and everything seemed OK. But, when I now turn the AC on, the driver side blows warm air (outside temp.) while the passenger side has cold air. What may the problem be? Would it be possible that some small pieces of leaves went into inside of the system, which means the dealership will be responsible for a repair?

Answer
YG,
I hate to say it, but I do not foresee this being something the dealer might have done. Even if there was a leaf or two inside the venting system, it would restrict the flow of air, just a hair, it would not change the temperature of the air coming out to the extreme you are describing.
I believe that what has happened is on of your blend doors is not opening. This could be due to the actuator/motor being bad, or it may not be receiving the correct signals to open from your control head.
Some systems are activated by a series of vaccuum lines controlled by a vaccuum manifold. If this is the case with your toyota, then a vaccuum line may have disconnected from the actuator, disconnected from the vaccuum control manifold, or your VCM is going bad and not activating the line to your passenger side blend door. Or again, the VCM may not be geting the correct signal from your control head.
Or your system may be controlled by a series of electronic logic control circuits, in which case, I won't even get into all of the possibilities.
I would recommend you take your sienna to a reputable shop, or even back to the dealer so they can troubleshoot it. They have the equipment, and it may be a common fault that they see fairly often with the Siennas. And who knows, the dealer may see a loyal returning customer and cut you a small break. You never know. But that is my recommendation. Sorry I couldn't be of more help.