The answer to 'why is my HVAC system blowing hot air' is that there are several common causes, including a malfunctioning compressor, low refrigerant levels, or an issue with the thermostat. These problems can lead to the HVAC system blowing hot air instead of cool air.
Some key symptoms to look for include the air coming out of the vents feeling warm or hot, the compressor not turning on, or the system running constantly without cooling the home. Potential solutions may involve recharging the refrigerant, replacing the thermostat, or repairing or replacing the compressor. However, many HVAC issues require the expertise of a professional technician, so it's important to call for service if you're unable to diagnose and fix the problem yourself.