You think the (new) monovalve insert is defective? I changed that on Saturday prior to the "No Heat" situation. Now it seems that I can get (very) hot air all the time (no matter what the temp dial says), and I get cool air only if I'm lucky. Question - will hot air "take over" if ac (charge) is low and compressor is not running? I have not checked this yet. Thanks again. I did say "cool" air.