Lennox Mini Split P1 Error Code

Updated 2026-08-30 · review status: manual-verified · reviewed by MiniSplitDecoder Editorial Team Last verified: 2026-08-30

Check your model first

  • Lennox outdoor (Service Manual 100030, Section 5.8, P1/PC 30)
  • Lennox indoor (100030 Section 6.17, P1/PC 01)
  • Midea-built platform (Midea P1 sheet / MRCOOL PC 01)

Match the model on your equipment label to the linked manufacturer documentation. The same code can mean different things across model families.

Quick answer

P1 on Lennox mini splits means high-pressure protection: the high pressure switch opened (trips at 639 PSI, resets at 464 PSI) because of poor outdoor airflow, a dirty condenser coil, a failed outdoor fan, overcharge, or an over-temperature day. Some Lennox displays use P1 for the PC 01 high/low supply-voltage protection instead - confirm which display you are reading. One power cycle; pressure-switch, voltage, and refrigerant work is technician-only.

Severity: high · DIY difficulty: easy

Safety

Stop at the breaker power-cycle and any plug-accessible checks (filters, remote settings, visible wiring). The outdoor unit's capacitor holds a lethal charge and the refrigerant circuit is both pressurized and (on R-32 units) flammable — opening panels or servicing the sealed system is licensed-technician work (EPA 608).

What P1 means

P1 on Lennox mini splits means high-pressure protection: the high pressure switch opened (trips at 639 PSI, resets at 464 PSI) because of poor outdoor airflow, a dirty condenser coil, a failed outdoor fan, overcharge, or an over-temperature day. Some Lennox displays use P1 for the PC 01 high/low supply-voltage protection instead - confirm which display you are reading. One power cycle; pressure-switch, voltage, and refrigerant work is technician-only.

Code meaning varies by series

  • Lennox outdoor (Service Manual 100030, Section 5.8, P1/PC 30): P1 = high pressure switch open; trips at 639 PSI, resets at 464 PSI; sampling voltage must be 5 V
  • Lennox indoor (100030 Section 6.17, P1/PC 01): P1 (indoor display form) = high or low voltage protection (PC 01 family, e.g. supply voltage out of range)
  • Midea-built platform (Midea P1 sheet / MRCOOL PC 01): Over-voltage or too-low-voltage protection - same platform voltage-protection family

First checks before service

This page currently documents the safe reset triage. If the code returns, use the linked source manual or a qualified technician for code-specific diagnosis.

  1. 1. One-time fault event (power disturbance or transient sensor reading) common DIY

    Check: Power-cycle at the breaker/disconnect (or unplug for CPAP), restore, and run the system while watching for the code.

    Fix: If the code does not return after a full run cycle, the fault was transient — monitor, no repair needed.

  2. 2. Fault persists after a clean reset occasional pro only

    Check: If the code returns immediately or every session, note the conditions (startup, heating, after rain).

    Fix: A persisting code points at the component the manual assigns to this code — that repair is technician territory.

Related codes

Cross-references for the same fault family, by brand:

Lennox P2 · Lennox P3 · Lennox F0 · Lennox EC07 · Lennox EL01 · Lennox F5

Commonly searched as: "lennox p1" · "lennox error code p1" · "lennox air conditioner p1"

Sources

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