Digital thermostat mounted on a concrete wall
Generic photo: Alexander Mass · Pexels License

Auxiliary heat runs too much or all the time

Aux heat should only help when the heat pump cannot keep up. Constant aux usually means wrong wiring/settings (aux on the heat pump terminal, emergency heat left on), big setback recoveries, or a heat pump that is not producing heat.

Single source ~45 min moderateBrands: All

Before you start

  • Heat strips are 240 V: low-voltage checks only unless qualified
  • Refrigerant-side diagnosis is refer-out (EPA 608)

Diagnostic steps

Unlock all 4 steps with expected values

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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Auxiliary heat runs too much or all the time · OnCall Tech