It's a 2004, w/ dual zone automatic heating/cooling. I only get heat, and it's max hot, when I set the temp to max (90degF). If I go one click lower to 85degF I get ambient air temp coming out, no heat at all. Does this on both sides, and you can have hot on one side and cold on the other and vice versa. So I don't think it's the blend doors. However, it showed a 2266 code stored (left blend door I think?) but no codes when it ran through the self-test. I'm also having other strange electronic gremlins that may or may not be related. Outside air readout usually shows in the 100's deg F always like 187. Cruise control worked intermittently for awhile and also had all center console lights go out, no displays for heat, radio, button lights, but if you press the buttons you can still turn work the climate control... all that went away a few months ago, but this hot or nothing issue still remains. Any ideas out there? ECM? Some circuit board or control somewhere?

 

So after checking and clearing the codes and running the self test, it's back to working normally. Strange! This problem has existed for years and has even been into a dealer for it (last owner) who quoted some crazy expensive electronic parts to fix it. $0 some research, and 5 min!