Temperature Control Doesn't Work

[SeaDuck79]

So either my car's bi-polar or there's a problem. The only way to get warm air to come out is to put the temperature control on max. Anything else is ice cold.

We don't use the "Auto" function - it's always setting a temp, and it worked fine until the battery ran down to dead one day (overhead light left on for a week).

Lexus dealer said they couldn't find a problem with the ECM. Any ideas on what I should tell them to do next time we take it in?