Lennox SCA Fault Code E18
Lennox SCA Fault Code E18 is a critical safety alarm indicating: High pressure safety 2. The most common causes include Condenser 2 fouled. Estimated repair time: 1-2 hours. This alarm requires immediate attention by a certified HVAC technician.
Alarm Description
High pressure safety 2
Brand: Lennox | Model: SCA (Air-Cooled Scroll Chiller) | Code: E18 | Severity: Critical
Observable Symptoms
- Compressor shuts down on high pressure safety cutout
- Discharge pressure gauge reads above normal operating range
- Condenser may feel hot to touch or airflow feels restricted
What to Check First
Before diving into detailed diagnostics, start with this quick first check:
Probable Causes
- Condenser 2 fouled
- Non-condensables on circuit 2
- Refrigerant overcharge on circuit 2
- Fan 2 failure
Recommended Inspection Steps
- Clean condenser 2
- Check non-condensables on circuit 2
- Verify charge on circuit 2
- Check fan 2
Required Tools & Equipment
- Coil cleaning brush and coil cleaner
- PT chart for refrigerant type
- Safety PPE (gloves, safety glasses, face shield)
Estimated Repair Time
1-2 hours
When to Call a Professional
- If the fault persists after completing all recommended inspection steps
- If you observe unusual noises, vibrations, or oil leaks from the compressor
- If refrigerant charge levels are outside OEM specifications and EPA-certified recovery is needed
- If electrical measurements show voltage imbalance greater than 2% between phases
- If the fault recurs immediately after reset, indicating an unresolved safety condition
- Contact an authorized Lennox service representative for warranty-covered repairs
Related Fault Codes
Other Lennox SCA codes that may be related:
OEM Service Manual Reference
OEM Reference: Lennox SCA Air-Cooled Scroll Chiller Service Manual. Available through Lennox Commercial technical support.
Frequently Asked Questions
What does Lennox SCA fault code E18 mean?
Fault code E18 on a Lennox SCA chiller indicates: High pressure safety 2. This is a critical safety alarm that requires diagnostic attention.
What causes Lennox SCA alarm code E18?
Common causes include: Condenser 2 fouled; Non-condensables on circuit 2; Refrigerant overcharge on circuit 2
How do I fix Lennox SCA error code E18?
Follow the recommended inspection steps below. Start with the quick check, then proceed through each step. If the fault persists after all steps, contact an authorized Lennox service representative.