My 2004 Sienna has developed a problem with the heating system.
hockingzig
Member Posts: 4
When I turn on the heat, I only get hot air through the drivers side vent,the passenger side vent is very cold. I had it in to be worked on (at a Non-Toyota shop)and they tore it completely apart and could not diagnose the problem. It affects the entire system,meaning the air going to defrost is also hot on the drivers side and cold on the passenger side. Any ideas what the problem might be?
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Best Answer
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thecardoc3
Member Posts: 5,842
There are no TSB's for this issue, and the HVAC controller is not flash programmable. The system does use dual air mix dampers and servo motors. It also requires accurate feedback form the in-car temperature sensors for the control head to command the air mix doors to be positioned correctly. You are going to need a shop that specializes in this kind of repair and either has the Toyota Techstream or Techstream Lite scan tools. None of the aftermarket tools fully support the system. The tech will need to ensure that the in-car sensors are reporting correctly, and then confirm that the control head is even trying to command the actuators to move.5
Answers
http://repairpal.com/heating-ac
AC/Heater Control Module
An AC/heater control module is a computer that controls and automates the operation of the heating, ventilation, and air conditioning systems (HVAC).
Symptoms of Wear or Failure
HVAC system might not heat or cool properly
Air distribution from the HVAC may be incorrect
Related Repair Advice
Fault codes stored in the HVAC control module should be reviewed as part of any HVAC system diagnosis
As with most computer controlled systems in modern vehicles, the climate control system may need occasional software updates to address various issues. A quality shop will check with the manufacturer to see if there are any Technical Service Bulletins (TSBs) related to the problems you're having and will upgrade the software when possible.