Munters HUM SNS ERR

What does Munters HUM SNS ERR mean?

On a Munters Smart C/D climate controller, HUM SNS ERR signals a fault in the humidity sensor. The manual states humidity sensor number 1 is either out of order or disconnected, so the controller cannot read a valid humidity value. The alarm appears on the main screen, shown alternately with the normal display until the problem is resolved.

Symptoms

• HUM SNS ERR alarm displayed on the main screen
• Humidity reading is invalid or absent
• Alarm relay triggers and repeats until the fault is cleared
• Humidity-driven functions do not operate as expected

Common causes

• Humidity sensor number 1 is out of order
• Humidity sensor number 1 is disconnected

Diagnostic steps

1. 01

   Acknowledge the alarm

   Press OK on the main menu to reset the alarm relay; the manual notes the message continues until the issue is resolved.

2. 02

   Check the humidity sensor connection

   Inspect the humidity sensor wiring for a disconnected lead, a cause given in the manual.

3. 03

   Replace a failed humidity sensor

   If the humidity sensor is out of order, install a working sensor.

4. 04

   Confirm the sensor is installed

   The manual notes the Target Humidity option appears only when a humidity sensor is installed, so verify the sensor is present and wired.

5. 05

   Disable the alarm only if the sensor is removed deliberately

   Per the manual, a deliberately removed sensor's error alarm can be disabled via the Calibration menu.

When to call a professional

The Smart C/D manual cautions not to open the controller box when a hardware problem arises and to contact an authorized electrician. Call a qualified technician if the alarm persists after checking the humidity sensor connection, if you cannot safely access the wiring inside a mains-powered enclosure, or if replacing and recalibrating the sensor is beyond your experience.