Um...what is "not true" about my statement? <img src="/forums/images/graemlins/confused.gif" alt="" /> Because it is absolutely true for three of the last four vehicles I have owned, and the fourth one I never bothered to find out.

Below a certain temp (probably at a different set point for each maker, cartainly below freezing), by design the AC does not engage in the defrost position because there would be no point. When the dewpoint is below freezing the evaporator simply cannot get cold enough to remove any moisture.

In warmer weather, then yes the AC does engage for defrost.