Question about 2005 Toyota Highlander

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2005 highlander heater problem

The heat goes cool at high temp setting . Moving the temp control up and down and it works good again for a short time. The two heater lines going thru the firewall are hot. Engine temp. is constantly normal. Coolant is full and under pressure. Any suggestions ?


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  • wmartin259 Sep 11, 2009

    Thanks for the reply. The nut was loose causing the 3 wire ribbon cable to break at the solder connection on the control unit. Toyota should have used braided wire instead of solid wire. Replaced the short ribbon cable with 3 separate pieces of good braided wire. Works great now. Thanks again

  • Superbovine May 11, 2010

    Pull the temperature knob off and verify the thin 12mm nut is installed and tight behind it. I have seen several of these loosen up allowing the knob to turn but intermittently have no effect on temperature. Failing that it sounds like a blend door motor malfunction or logic control malfunction and would require some hands on testing.

  • Sami Haddad
    Sami Haddad Oct 24, 2013

    I have 2005 Toyota Highlander 2.4 CC front drive , the problm is the blower blow only cold air no heat al t all



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I'm glad I could help. I'm reposting the solution below in case anyone needs it in the future. Please be sure to rate it for me!

Pull the temperature knob off and verify the thin 12mm nut is installed and tight behind it. I have seen several of these loosen up allowing the knob to turn but intermittently have no effect on temperature.

Posted on Sep 11, 2009


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