Heat Pump Not Heating

On a hvac unit, the symptom of "heat pump not heating" is one of the most frequently reported homeowner complaints — and it almost always traces back to a small set of root causes that you can investigate in under fifteen minutes without specialized tools. In heat mode, the indoor unit blows neutral air and never reaches setpoint, even at moderate outdoor temperatures. Before opening any access panel, unplug the appliance (or shut off the gas where applicable), give it a few minutes for residual current to bleed off, and have a flashlight, a phone camera for documenting cable routing, and a small bowl handy for any water that may release when you disconnect a hose.

Most service technicians work through the same checklist for this complaint, and the order matters because each successive cause requires more disassembly. 1. The system is in defrost mode — heat pumps temporarily reverse to clear ice from the outdoor coil. 2. The reversing valve has stuck in cooling position. 3. Outdoor temperature is below the system's published heating cutoff. 4. Refrigerant charge is low. Walk these in order and stop as soon as one of them resolves the symptom — there is no need to keep digging deeper if an early-list fix restores normal operation.

Practical do-it-yourself steps you can attempt safely: Step 1: Wait through one full defrost cycle (roughly 5-10 minutes) and observe whether normal heating resumes. Step 2: Check whether emergency or auxiliary heat (where available) brings the room up — this isolates the heat pump from the controls. Step 3: Confirm outdoor temperature is within the heating range listed on the data plate. After completing the steps, run a short empty cycle to confirm the symptom is gone before reloading the appliance with laundry, dishes, or food. Document anything you replaced — if the same fault returns within a few weeks, the technician will want to know what has already been ruled out.

When to escalate to a service technician: A stuck reversing valve is a sealed-system component — diagnosis and replacement are professional work. If the unit is still under the manufacturer's parts-and-labor warranty, do not perform any repair that involves opening a sealed system, breaking a tamper sticker, or substituting a non-OEM part — any of those can void coverage. Keep the model number printed on the rating plate and the date of purchase ready when you call; a competent technician can usually narrow the diagnosis over the phone if you describe what you have already tried.