AC only blows cold with recirc on

[dukbludvl]

I just bought a used (new to me) 2003 GMC Yukon.  It's my third Yukon from the 00-06 generation.  This one happens to have dual auto climate control.  I've found that the AC only blows cold when the recirc button is on -- and when it's running like that, the little snowflake icon is not lit up on the HVAC screen.  If I just turn on the AC (no recirc), the snowflake icon lights up, but the air that blows out is lukewarm -- not hot, just not cold either. 

 

Anyone have any idea what might be going on here?