I have a 2002 Trailblazer LT with manual comfort controls. When it is cold outside the heater works fine when the Mode **** is in Panel mode, or Bi-Level mode, and the Recirculation button is Off. The problem is, when I turn the Recirculation button On, the A/C compressor clutch kicks in even when the A/C compressor button is turned off. This not only cools the warm air down, it also decreases my gas mileage. Why would the A/C compressor kick in when it is not needed? Is this normal, or do I have an issue? I was thinking of installing a manual on/off switch in the power supply lead to the compressor clutch, but I shouldn't have to do this. Is there a better way to solve the problem? I really like having the recirculation button on to eliminate exhaust fumes and other odors from outside.