A/C controls do not work?

Tiny
BELTFED
  • MEMBER
  • 2005 TOYOTA SEQUOIA
  • 4.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 66,000 MILES
Climate control panel not working
Tuesday, July 11th, 2017 AT 7:13 PM

34 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,230 POSTS
Hello,

Is sounds like a fuse or the MG circuit control relay. Here are some guides and diagrams (below) to help you do some testing and get the problem fixed.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (Below). Please let us know what you find.
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Wednesday, July 12th, 2017 AT 11:15 AM
Tiny
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Checked fuses and MG relay. All good so far
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Friday, July 14th, 2017 AT 7:04 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,230 POSTS
Does the system have power?

Check the A/C fuses:

Test the A/C control panel:

Check the A/C blower motor:

Inspect the A/C compressor:
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Friday, July 14th, 2017 AT 9:36 AM
Tiny
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Checked connection at compressor. No power
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Friday, July 14th, 2017 AT 11:42 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,230 POSTS
If the fuses are good and the relay is good, then you will need to check the wiring.

https://www.2carpros.com/articles/how-to-check-wiring

If this checks out then the controller is bad and needs to be replaced.

Please run some tests and get back to us we are interested to see what it is.

Cheers, Ken
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Monday, July 17th, 2017 AT 9:30 AM
Tiny
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Is this referred to as the a/c integrated control panel? The a/c went out at the same time as the coolant temp gauge. After researching, it appears the coolant temp info is also sent through the same a/c integrated control panel. Does this make sense?
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Monday, July 17th, 2017 AT 11:51 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,230 POSTS
Yes it sure does, it sounds like the control panel is bad.

Please let us know what happens.

Cheers, Ken
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Tuesday, July 18th, 2017 AT 9:32 AM
Tiny
DAVID SPRIGGS
  • MEMBER
  • 2 POSTS
Same issue for me. I got another panel from LKQ and it also doesn't respond. All fuses tested and are good. Has anyone solved this issue yet?
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Monday, August 19th, 2019 AT 6:07 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,230 POSTS
We need to check for power at each of the system fuses not that the fuse is good the test is for power at the fuse. here is a guide and the fuse locations. Htr, CIG, Dome, Heater, RR heater and COS fan.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (below). Please let us know what happens.
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Monday, August 19th, 2019 AT 4:13 PM
Tiny
DAVID SPRIGGS
  • MEMBER
  • 2 POSTS
Took it to a shop today, gave them both units and explained the situation. They got back to me today and said that the harness is not giving power to the unit. So they found a short/broken wire near the connector and fixed it, everything works now.
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Monday, August 19th, 2019 AT 7:33 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,230 POSTS
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help.
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Tuesday, August 20th, 2019 AT 9:44 AM
Tiny
JIMDONSMITH
  • MEMBER
  • 4 POSTS
  • 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?
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Saturday, October 10th, 2020 AT 9:29 AM (Merged)
Tiny
HMAC300
  • MECHANIC
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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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Saturday, October 10th, 2020 AT 9:29 AM (Merged)
Tiny
JIMDONSMITH
  • MEMBER
  • 4 POSTS
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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Saturday, October 10th, 2020 AT 9:29 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 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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Saturday, October 10th, 2020 AT 9:29 AM (Merged)
Tiny
JIMDONSMITH
  • MEMBER
  • 4 POSTS
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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Saturday, October 10th, 2020 AT 9:29 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 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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Saturday, October 10th, 2020 AT 9:29 AM (Merged)
Tiny
JIMDONSMITH
  • MEMBER
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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, October 10th, 2020 AT 9:29 AM (Merged)
Tiny
LINDSAY NEAL OBERG
  • MEMBER
  • 4 POSTS
  • 2001 TOYOTA SEQUOIA
  • 4.7L
  • V8
  • 4WD
  • 184,000 MILES
I have the SR5 model. AC panel lights up but neither the temperature nor the fan speed knobs do anything at all. None of the other climate control related buttons respond either, however, the 4WD, VSC and hazard buttons work. Fuses are all good. Any ideas?
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Saturday, October 10th, 2020 AT 9:29 AM (Merged)
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
Our pleasure. Happy to help. Closing thread.
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Saturday, October 10th, 2020 AT 9:29 AM (Merged)

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