Why Won’t My Heat Pump Blow Hot Air?The Exterior Condenser is Dirty. After years of use, all exterior condenser coil will eventually accumulate dust and debris restricting airflow.There’s a Blockage Outside. If you have plants around the edges of your heat pump’s vent outside, then you’ll undoubtedly experience troubles.The Filter Might Be Clogged. …There’s a Low Refrigerant Charge. …More items…