♻️ Auxiliary Heat Control Repair, Georgetown TX

A heat pump's compressor loses heating capacity as outdoor temperatures drop, and below roughly 30 to 35 degrees Fahrenheit it often can not keep up with the home's heat loss on its own. Auxiliary heat, sometimes called strip heat or electric resistance heat, is a bank of electric heating elements built into the air handler that energizes to make up the difference. On most systems this is controlled by a heat sequencer or the outdoor thermostat, which reads either the outdoor ambient temperature or the discharge air temperature and stages the strips on in steps rather than all at once, both to limit the electrical inrush and to only add as much supplemental heat as is actually needed.

When auxiliary heat control fails, it usually shows up in one of two opposite ways. A stuck or welded relay contact, or a sequencer that fails closed, keeps the strips energized continuously even when the compressor alone could satisfy the thermostat, which drives electric bills up sharply without an obvious comfort complaint. The other failure mode is a blown fuse, tripped high-limit switch, or failed sequencer that never lets the strips engage at all, so the home simply can not reach setpoint during cold snaps even though the compressor is running normally. There is also the emergency heat setting on the thermostat, which manually locks out the compressor and runs on strip heat alone. It is meant as a temporary override when the compressor or reversing valve has failed, not a setting to leave on, and we frequently find it switched on by accident.

Repairing auxiliary heat control starts with confirming the outdoor thermostat or board's ambient sensor is reading accurately, then tracing the W2 and E terminal wiring to the sequencer or heat relay board, testing each stepping relay's coil and contacts, and ohming out the resistance of each heat strip element against the manufacturer's chart. We also check the high-limit safety switch mounted on the strip assembly itself, since a dirty filter restricting airflow across the strips can trip this switch and mimic a control failure. On the electrical side we verify the breaker amperage matches the total kW rating of the strip banks, since older Georgetown homes built before heat pumps were standard sometimes have panels sized without that extra load in mind, and a hard freeze that pushes strips into heavy use can be the first time an undersized circuit gets tested.

Replacement parts vary by what failed: a sequencer or control board typically runs $150 to $450, while a full heat strip element bank replacement runs $200 to $600 depending on the kW rating installed.

Heat Pump Not Working?

We service all heat pump brands and carry common parts on every truck.