I was using my AC today (I live in South Texas) and suddenly it stops working. I shift the vent to a higher setting, nothing. I finally shift to the highest setting and I get plenty of air (The AC works) but only at the highest setting. I also checked the other settings (heat, defrost, etc) as well and the same thing; nothing works unless I have blower on max. Weird! What can be causing this? I have a 2000 SVT.