Heater does not work

RICHARD SIMPSON

MEMBER
2003 TOYOTA SEQUOIA
130,000 MILES

The temperature control knob works from max cool to hot but the control valve is not opening. I unhooked the cable and opened the valve manually, but the blend door is not working either so it still blows cold air. Any help would be appreciated.

Thursday, January 11th, 2018 AT 7:12 AM

4 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,380 POSTS

Hello,

It sounds like you may have a fuse out (CIG or HTR), this is what I would check first. Here is a wiring diagrams for the air conditioner and the fuse panel locations and diagrams as well:

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

Check out the diagrams (below).

Please run this test and get back to us.

Cheers, Ken

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Friday, January 12th, 2018 AT 1:39 PM

RICHARD SIMPSON

MEMBER
3 POSTS

Sorry it took so long to get back with you I just got to where I could check the fuses. Both fuses are good and have power. I can pull the cig fuse and it has no effect on the problem the temp read out works from max cool to hot, the mode changed from panel to floor. When I pull the htr fuse the only thing that doesn’t work is the blower everything else works according to the controls but still no control valve function or blend door operation. I am having trouble following the wiring diagrams but any other suggestions will be appreciated

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Wednesday, January 24th, 2018 AT 10:00 AM

RICHARD SIMPSON

MEMBER
3 POSTS

Any thing else that I can check

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Wednesday, January 24th, 2018 AT 10:04 AM

KEN L

MASTER CERTIFIED MECHANIC
48,380 POSTS

It sounds like the controller is out to me. I would see if the control head is getting power and ground to confirm the failure.

Here are more diagrams to help us see how the system works.

Please run some tests and get back to us.

Cheers, Ken

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