What controls the fan on my heat pump? It's running all the time, whether the compressor is running or not, and I can't tell from the diagram on the back of the shroud what actually tells the fan to shut off when temp is reached and the thermostat shuts down the compressor.

The fan on a heat pump usually shuts off unless it is wired wrong. If the fan motor has been replaced it is possible someone wired the fan to the wrong side of the contactor.

Thanks. I installed a new contactor and that's when the problem started. It wasn't the same brand, and so I can see now how I may have installed it backwards. I'll try swapping it around.

Good idea. This kind of thing does happen.

Yeah, hooked it up backwards. Works great now. Fan is controlled by power, and the power was a straight shot to the capacitor. Now, the contactor has to be energized for the fan to get power.
Striving to better, oft we marr what's well.

Glad you got it going.