Have Toyota Questions? Ask a Mechanic for Answers ASAP
Hello my name is***** am an ASE Master Technician and I am glad to help you with your question.
Make sure you have no air pockets in the cooling system, bleed the air from the cooling system and make sure it is full. Also check that both lines coming out of the heater core are both hot. You may have a clogged heater core of a water pump problem. If the engine runs hot I would look at a water pump issue. If not the heater core is probably the problem. I have also seen this problem caused by a stuck or broken blend door.
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