CodeRegistry
Brands
  1. Home
  2. Lennox
  3. PRODIGY 2.0 Unit Controller
  4. 18
About·Privacy·Terms

CodeRegistry — Your global library for technical solutions.

For your safety: always follow the equipment manufacturer’s official manuals. CodeRegistry is an independent help site and is not affiliated with the brands listed here.

18

Alarm 18 - High Pressure Switch S96

Lennox · PRODIGY 2.0 Unit Controller

What does 18 mean?

The S96 high pressure switch has opened due to high system pressure. The corresponding compressor is de-energized for a set delay.

Common Causes

  • High system pressure
  • S96 high pressure switch malfunction

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check for conditions causing high pressure, such as restricted airflow or overcharging.

  2. 2

    Allow the system pressure to drop; the switch should reset automatically after a delay.

  3. 3

    If the issue persists, check the S96 high pressure switch for proper operation.

Browse all codes in this manual (56)
Verified technical data. Last updated: April 2026

Related Faults

12Alarm 12 - High Pressure Switch S414Alarm 14 - High Pressure Switch S716Alarm 16 - High Pressure Switch S28
Source: Lennox PRODIGY 2.0 Unit Controller
Open Manual (Page 11)Search more codes in this manual