Alarm 40 — Return air temperature too high for heating

What does 40 mean?

This alarm is displayed when the return air temperature exceeds the limit set for heating mode. The alarm code is shown but not stored in memory for recall. Parameter 115 (HEAT RET AIR LIMIT) defines this limit.

• Return air temperature is excessively high during a heating demand.
• Incorrect setting for Parameter 115 (HEAT RET AIR LIMIT).
• Problem with the return air temperature sensor.
• Unit is attempting to heat in an environment that is already too warm.

Click steps to track your progress.

1. 1

   Check the current return air temperature.

2. 2

   Verify the setting of Parameter 115 (HEAT RET AIR LIMIT).

3. 3

   Ensure the return air temperature sensor is accurate.

4. 4

   Investigate why the return air temperature is too high for heating.