It will only blow heat if it feels it's required to reach your current temperature setpoint.

It can't blow heat all the time, otherwise it will reach your setpoint and keep heating right past it.

Domestic Heatpumps have quite unusual dead bands in the modes, so often the room temperature has to stray quite a long way from setpoint before it will switch modes from heating to cooling etc, or vice versa.

To test, ensure the mode is specifically set to heating (not auto) and you select a setpoint much higher than the current room temperature.  Once you've proved hot air can be produced by the unit, put it back into auto mode, select a sensible room temperature like 21/22deg and kick back with a beer to watch the rugby.