My heat pump, set to cool the house, is instead cooling mother nature and heating up our house. It worked just fine yesterday; not a thing has changed. Any ideas?:confused:

Reversing valve is stuck, reversing valve coil is bad, or voltage to revering valve is not changing (24 to 0 or 0 to 24 vac) when the mode is chnaged from heat to cool.

After checking voltage at the valve, you can LIGHTLY tap it.

Hope the tech / installer did a proper pull down on install non-condensable do strange things