Two problems related to defogger have been reported for the 2005 Toyota Highlander. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 Toyota Highlander based on all problems reported for the 2005 Highlander.
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.
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.