What are the symptoms when the a/c temperature control knob goes out?
Asked by Papafris Jul 18, 2015 at 05:49 PM about the 2005 Toyota Highlander Base
Question type: Maintenance & Repair
When I touch the temperature control knob the air will go from cold to hot and back again.
Even when I step on the brake suddenly the air will change from cold to hot. Is there a way
to tell if it is the control or something else?
7 Answers
firebird338 answered 8 years ago
The blend door cable has come off or has come loose. This is the door in the heater box that switches from the heater core box for heat and evaporator for A.C.
escalante1 answered 8 years ago
I had a similar problem when i bought my Demo 2005 Highlander. After taking to the dealer twice, i decided to explore behind the temp. control, I found then some wires from the control to the electronic board were broke because of bad installation at the factory. I unsolder the wires from the board rearrange the harness to relieif strain on the bundled wires to the board and resolder the wires. One problem gone (Disclosure- I was trained as an electronic technician in the USAF). I hope it solves your problem.
Some conetion on the nob is detached. Meaning the soldering is out . Will need to open the panel that holds the nobs and then solder them back. That why it keep on going on and off because when you hit the break it possibility touches the connection and the come off. Try that I did it to my car and it worked. Never had problem again. Good luck. Francis.
Escalante's answer 2 is what I experienced as well, however this is not a bad factory installation. It is caused by the nut under the control knob coming loose from constant adjustment and the control module shifting behind the knob, on the circuit board and damaging the connection behind. It is a time consuming but simple repair for someone with electronic experience. Your dash panels will come off to reveal the radio and heater controls behind. You must be patient and gentle if attempting to open this panel. You should not attempt to repair the circuit board unless you have exoerience and the correct needle tip soldering iron... not a soldering gun, a precision fine detail iron. You can also find repaired boards on line. A dealer cannot perform this repair, only replacement of the panel.
guajira273 answered 4 years ago
My 2002 Highlander had the same problem. Shop estimated $1000 fix ant 4 yrs ago. But I found this thread & decided to try DIY fix. https://www.tundrasolutions.com/threads/heater- quit-sort-of.14033/ Located the ribbon wire behind middle dial on circuit board. Paid a guy $10 to resolder all 3 wires to board. Reinstalled. It's been working great for 4 yrs.
Sometimes only need to pull of the heat/cool know and tighten down the nut at the base of the control stem
That is, take the knob off, tighten up the nut at the base. The get loose at the sweeper connection isn't making connection at all times
