Typical outdoor temps are in the 40s-50s. It seems like the aux light always is coming on with the heat pump. I realize if the freon is low, or the heat pump is not operating efficiently, stage 2 will be called upon. How do I determine that in fact, Aux is needed?

You will have to have the heat pump tested to see if it is operating correctly and at full capacity then you will know.

You will have to have the heat pump tested to see if it is operating correctly and at full capacity then you will know.

I was afraid of that. I was hoping there was a way around the service call. I'm familiar with the concept/workings of a heat pump and its limitations requiring the need of the Aux heat. But, thanks all the same.

Sometimes you have to call since the emergency or aux heat usually comes on for a reason and if you do not know if the heat pump is running correctly it makes trying to figure out the problem all the more difficult. Good luck.

Sometimes you have to call since the emergency or aux heat usually comes on for a reason and if you do not know if the heat pump is running correctly it makes trying to figure out the problem all the more difficult. Good luck.

Thanks and OK. I was thinking if there was an outside temp "window" that the heat pump should be able to work w/o calling on stage 2 and use that for a guideline. See you.

There is and it is called the balance point but the balance point is different for every location, house, and it also depends upon how the system was originally setup.