Lennox Air-conditioner 411 Error Code — Meaning & Repair Cost (2026)
Low pressure switch has opened five times during one cooling or heating demand and the outdoor unit is locked out. Below: the most likely causes, and what the matching repair costs — Estimated national ranges with a metro localizer. Reviewed July 2026.
What 411 means
Low pressure switch has opened five times during one cooling or heating demand and the outdoor unit is locked out.
Likely causes, most common first
- Refrigerant undercharge or leak
- Restricted airflow across the indoor coil
Base: 1 published national repair-cost guide (retrieved 2026-07) · full source registry on the methodology page · Code meaning & causes · Reviewed July 2026
What it usually costs to fix Estimated
411 on a Lennox air-conditioner resolves to the central air conditioning refrigerant leak repair / recharge problem. Lennox parts typically run ×1.35 against the mainstream baseline (Lennox 'uses proprietary parts that only Lennox dealers can source.' A direct brand comparison found a blower-motor replacement running $2,400-$2,500 installed on Lennox vs $600-$1,200 on Carrier, with Lennox parts needing to be special-ordered direct from the factory (2-4 week wait) versus same-day local-supplier availability for Carrier parts.), and the ranges below already include it.
$335–$2,985 national estimate to fix the fault behind 411 (Lennox parts ×1.35). Enter a ZIP to localize.
| Most common repair | Typical total | DIY? |
|---|---|---|
| Leak detection + braze/patch repair (line or coil joint) | $435–$1,340 | Pro recommended |
| Refrigerant recharge only (R-410A top-off, leak already sealed or minor) | $335–$1,075 | Pro recommended |
| Evaporator / condenser coil replacement (leak is in the coil itself) | $1,340–$2,985 | Pro recommended |
Plus a typical service-call / diagnostic fee of $75–$150, often credited toward the repair.
Pick a quality tier for a class-typical estimate, or a specific brand to override it (brand adjusts the parts portion only). Enter a ZIP or Canadian postal code to localize to your metro's labor costs. Everything updates without a page reload; no data leaves your browser except the shard lookup.
Base: 3 published national repair-cost guides (retrieved 2026-07) · full source registry on the methodology page · National base range (BLS OEWS May 2025 + BEA RPP 2024) · Reviewed July 2026 · Estimated
Codes are universal — your location changes the repair price, never the code's meaning. See the methodology for the exact localization formula and sources.
Reviewed by a Red Seal–certified appliance technician who also holds a Technical Safety BC gas ticket (Gas-C) and an ODS/halocarbon refrigerant ticket (CFC/HCFC/HFC).