I HAVE A 2003 TOYOTA SEQUOIA LIMITED. TEMPERATURE CONTROL ISSUE

  • Tiny
  • jimdonsmith
  • 2003 Toyota Sequoia
  • 162,000 miles

When I turn the temperature control **** to max cold. The heater control valve goes all the way to the top and cold air blows. When I adjust the temperature off of "max". Even by just one degree. The heater control valve goes all the way to the bottom and hot air blows. So it seems that it is either all up or all down. I assume it should vary to allow cooler or warmer temperatures to come through heater core. I guess the heater control valve is ok and the control cable is ok. So is my problem the temperature control electronic parts are something different?

Wednesday, November 9th, 2011 AT 11:42 PM

7 Answers

  • Tiny
  • hmac300
  • Expert
  • 42,166 posts

In american cars they are actuators but in yours they are servo motors. I've included a pic see if they are working corrrectly, especially the air mix one

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Wednesday, November 9th, 2011 AT 11:47 PM
  • Tiny
  • jimdonsmith
  • Member

Thanks for the quick response. Is there a way to determine if the problem is the servo or the actual control ****?

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Thursday, November 10th, 2011 AT 8:11 PM
  • Tiny
  • hmac300
  • Expert
  • 42,166 posts

If it's vacuum turn the control toheat and see if you are getting vacuum. If you are and it's not working then it's the servo. If it's electricyou'll have to do the same but use a test light or vom

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Thursday, November 10th, 2011 AT 8:57 PM
  • Tiny
  • jimdonsmith
  • Member

Ok. I still have no clue. I changed the air temperature control and the problem remains. What regulates the air mix servo? If it is only working from all hot or all cold. Then a relay, resister or some sort of module must tell it to stop in the middle to allow the air to mix to "warm". Any information would be greatly appreciated.

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Thursday, December 1st, 2011 AT 4:10 AM
  • Tiny
  • hmac300
  • Expert
  • 42,166 posts

It's controlld by the control unit that says hot/cold. If it's vacuum it's how much is sent to it and if it's electrical ther ewill b a module inside teh control unit for it.

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Thursday, December 1st, 2011 AT 1:58 PM
  • Tiny
  • jimdonsmith
  • Member

OK. Got it figured out. When I took car to dealership to have them repair the ignition switch, they unplugged the thermistor and never plugged it back in. It was located under the driver steering wheel behind the temperature sensor vent. I plugged it back in and it works perfectly. Thanks.

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Saturday, December 10th, 2011 AT 1:39 AM
  • Tiny
  • rivermikerat
  • Expert
  • 6,118 posts

Our pleasure. Happy to help. Closing thread.

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Friday, January 27th, 2012 AT 3:51 AM

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