This problem was for the heating and a\C. this website tells of the problem in the manufacture of the vehicle: www.devalcourt.com/2010/03/fixing-2004-Toyota-Highlander-ac-and-heat-issue/. the way Toyota made the wiring (too short for the dial) was faulty in that, after repeated use (who doesn't use their heating and A/C regularly?) the wires would break off causing a short. Whenever we drive over a bump in the road, the A/C shifts to heat or the heat shifts to A/C. we used to remove the cover of the knob and tighten the hex nut there, but now that doesn't work. This is especially worrisome in the winter when the defrost shifts to A/C and the front window starts to "fog" up. This makes for extremely dangerous driving and inhibits your ability to see clearly and navigate the roads. This should be considered a design flaw by Toyota and should be recalled. Please note, on the website mentioned above -- there are many more year models (2001, 2004 were also mentioned) that are affected by this. Thank you!

- Williamsburg, VA, USA

Heater runs erratically--blowing fine and then switching to cold air and then if I "jiggle" the control can get heat again. Had the dealer repair in fall of 2009 (about $95), but it has started acting up again.

- Pittsburgh, PA, USA

2005 Toyota Highlander. Erratic temperature control from heater. When set on cool will suddenly blow hot air and vice versa. On-line complaints indicate this is a common problem resulting from defective control unit in this and other Toyota vehicles over several years. The control know comes loose and then the wiring behind it breaks from the circuit board resulting in erratic air temperatures. I also have concern that this electrical failure could cause other electrical shorts or problems. Dealer recommends replacement of entire control unit at prices ranging from $500 to $1500. On-line consumers report fix only requires resoldering the 3-wire contacts at a cost of a few dollars. It is obvious Toyota knows about this issue and the relatively easy fix documented with pictures on-line but continues to deny that it is their problem. It is a manufacturing defect that should have been dealt with several years ago, but charging owners huge fees for replacing a simple component seems to be what Toyota feels is the appropriate solution.

- Brewer, ME, USA