Why it matters to you
Houston heat pumps spend most of the year in cooling, so the reversing valve can sit in one position for months before the first cold front asks it to shift. A heat pump that blows cool air on the first chilly morning may have a valve or control problem — or may simply be running a normal defrost cycle.
Practical guidance
First confirm the thermostat is set to Heat and give the system several minutes, since defrost can briefly blow cooler air. If it keeps blowing cold in heat mode, call a licensed technician; testing the valve and its solenoid involves refrigerant pressures and live electrical circuits.