Heil air conditioner intermittently shuts off; thermostat or board shows E7 sensor fault

Safety first: Turn off power to the outdoor unit before accessing sensors or the control board.

• Step 1 – Locate sensors: On Heil condensers, the ambient sensor is typically clipped near the coil or grille; the coil sensor is attached to the refrigerant tubing.
• Step 2 – Inspect wiring: Check for broken, chewed, or sun-damaged sensor wires. Repair any obvious damage and reseat connectors on the control board.
• Step 3 – Check sensor resistance: With power off, disconnect the sensor and measure resistance with a multimeter. Compare to Heil service chart (resistance vs. temperature). If readings are far off, replace the sensor.
• Step 4 – Clear error: Restore power and cycle the thermostat. If E7 clears and operation is normal, monitor performance. If it returns, the control board may be misreading sensors and require replacement.