Trane heat_pump Error Code 4

What does 4 mean?

Outdoor temperature is below minimum operating threshold for cooling or heating mode.

Common causes

• Normal operation lockout in extreme cold
• Faulty outdoor temperature sensor
• Incorrect lockout temperature setting

Diagnostic & testing steps

1. 1. Check outdoor ambient temperature
2. 2. Cooling lockout below 55°F is normal
3. 3. Measure outdoor temperature sensor resistance
4. 4. Compare sensor reading to actual ambient temperature

Tools required

• Thermometer
• Multimeter

OEM parts & part numbers

Outdoor Ambient Temperature Sensor

Part numbers: SEN00885