Bosch EC error code

What it means

EC means low refrigerant. In plain English, the unit is detecting abnormal refrigerant flow, low refrigerant, or a cooling-system condition.

Urgency

Likely causes

1. Refrigerant leak or undercharge
2. Service valve not fully open or refrigerant flow restricted
3. Indoor or outdoor coil temperature is not changing as expected
4. Temperature sensor or control board is misreading the circuit

Homeowner fix

Turn the system off. Do not attach gauges, open service valves, add refrigerant, or keep resetting the unit.

When to call a pro

Call a licensed HVAC technician if EC returns after one safe reset or the condition will not clear. Tell them the official source lists EC as Low refrigerant.

Repair vs replace

Refrigerant and pressure problems are often repairable, but repeated leaks, inaccessible line-set damage, or compressor damage can make replacement worth comparing on older equipment.

• Bosch Climate 5000 A/B legacy R-410A 9,000 BTU Regular (BMS500-AAU009-1AHWXB / BMS500-AAS009-1CSXRA)

  Climate 5000 A/B legacy R-410A

• Bosch Climate 5000 A/B legacy R-410A 12,000 BTU Regular (BMS500-AAU012-1AHWXB / BMS500-AAS012-1CSXRA)

  Climate 5000 A/B legacy R-410A

• Bosch Climate 5000 Gen 4 R-454B 6,000 BTU Regular (BMS500-AAU006-1AHWXD / BMS500-AAS009-1CSXRD)

  Climate 5000 Gen 4

• Bosch Climate 5000 Gen 4 R-454B 9,000 BTU Max Performance (BMS500-AAU009-1AHWXD / BMS500-AAS009-1CSXHD)

  Climate 5000 Gen 4

For your technician

Technician note: leak check, verify valves, airflow, sensors, restrictions, evacuation, and weighed charge before clearing the code. Source: Bosch Climate 5000 G2 A/B IDU service manual Table 14 and ODU service manual Table 12; supporting diagnosis sections where listed; Table 12/Table 14; refrigerant leakage detection. Page context: Bosch maps this display to the Climate 5000 A/B legacy R-410A line; source: Bosch Home Comfort official Climate 5000 G2/A-B Ductless AC-HP IDU and ODU Service Manuals, wall-mounted error-code tables and diagnosis sections; display convention: match the letter E and letter C marker exactly before comparing neighboring codes.

Which systems show it

Climate 5000 A/B legacy R-410A

Related troubleshooting

Use the symptom guide alongside the exact display code if the unit is flashing, cycling, or showing comfort symptoms.

Related codes

Source

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