I have a 2007 RX400H and has now started to quit heating - periodically. It heats for a while then just starts to blow cold air. I have found some things on the UK site, but wondering if this is an issue in N.A. as well. Since it is -5 or better here heat is a bit important in my car at the moment. The fan blows great, and I have no other issues, and I have had heater cores go out in other cars and that is not the case. Any ideas are welcome.