Originally Posted by Zacharias

I'm not certain I am following this exchange, so here is another $0.02....

When defrost is selected, the system should operate at full heat and highest fan setting out the defrost vents only. There is no auto temp control and no way to reduce the heat output. That is how the system is designed.

In all other modes apart from defrost, you should be able to choose between manual control of fan speed or the auto setting, which operates the fan in concert with the auto temp control. You should also have auto temperature control, based on the setting of the adjustment wheel. Economy mode only differs in that the AC compressor engage on that setting.

In every other mode other than defrost, if you are selecting a temp and the system isn't shutting off when that temp is reached, there is an issue with one or more components.