The answer to 'why is my heat pump blowing hot air' is that your heat pump is likely in the wrong mode or has a mechanical issue. Heat pumps are designed to both heat and cool your home by transferring heat, but if it's blowing hot air when you expect it to be cooling, there could be a problem.
Some common causes include the heat pump being set to the wrong mode, a refrigerant leak, a faulty reversing valve, or a problem with the compressor. You'll want to check the thermostat settings first to ensure it's in the correct cooling mode. If that's not the issue, it's best to call in an HVAC professional to diagnose and repair the problem, as heat pump repairs often require specialized knowledge and tools.