One problem related to air conditioner has been reported for the 2008 Lexus GX470. The most recently reported issues are listed below.
I purchased a new Lexus GX 470 in November 2007. It always smelled musty. I took it to dealer two times and a 3rd party mechanic once. Lexus told me it was mold build up in ac unit. They said it occurred because I put the air flow on interior air flow only. Me and my 2 children have had asthma attacks and allergic reactions since the vehicle was purchased. They have had to increase their allergy medication and I have been put on a prescription.