The clicking noise is caused by eaither a bad blend door acuator or the blend door is bad but in most cases its the blend door acuator, they have a plactic gear in them that is know to strip out and that the noise due to the gear shipping. It is a fairly large job to perform without proper technical car repair knowledge.
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This will help.
Thanks.
See below latest heater related solved problem :----
Water getting collected into heater box on 2000 Toyota Camry?
http://repairhelpcenter.blogspot.com/2011/10/water-getting-collected-into-heater-box.htmlCar heater blowing warm, but not hot air?
http://schematicsdiagram.blogspot.com/2011/12/car-heater-blowing-warm-but-not-hot-air.html
Engine Overheats and heater blowing cold?
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http://howtobyme.blogspot.com/2011/12/replacing-heater-water-control-valve-on.html
How to replace heater core for All car models?
Click the link below:---
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