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Error code reference

Goodman Air Conditioner Error Code nP

Window Switch Lockout (LS & INN open)

Goodman codesGoodman air conditioner codes

Window Switch Lockout (LS & INN open) - unit will not condition space with door or window open.

First step from the service manual

Close Room Door or Window.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What nP means on a Goodman air conditioner

The nP error code on a Goodman air conditioner indicates a Window Switch Lockout condition. This code is triggered when both the LS (limit switch) and INN (indoor network node or interlock) contacts are simultaneously open, signaling to the unit's control board that a door or window in the conditioned space is open. The control system interprets this as an intentional ventilation event and suspends all conditioning operations to prevent energy waste and maintain efficiency. This is a protective interlock function, not a component failure.

The window switch circuit is designed to detect when an exterior opening compromises the conditioned envelope of the space. When the unit detects the open-circuit signal from both the LS and INN inputs together, it enters lockout mode and displays nP. The unit will remain in this state and refuse to heat or cool the space until the circuit condition changes. This dual-input requirement helps prevent false lockouts from a single intermittent contact.

In most cases, the fix is straightforward: close all doors and windows associated with the interlock circuit, and the unit should resume normal operation automatically. However, if the error persists after all openings are closed, the issue may lie in the switch wiring, a faulty door or window switch contact, or a damaged interlock circuit connection. In those cases, inspecting the wiring to the LS and INN terminals on the control board and testing the switch contacts for continuity would be the appropriate next diagnostic steps.

Source: manufacturer service documentation.

Common causes of nP

  1. 01

    Open Door or Window

    Wiring / connection

    The most common cause is simply that a room door or window monitored by the interlock circuit is physically open. Close all doors and windows associated with the unit and the lockout should clear automatically.

  2. 02

    Faulty Window or Door Switch Contact

    Part replacement

    The switch mounted on the door or window frame may have a worn, misaligned, or failed contact that reads as open even when the door or window is closed. Testing the switch for continuity when in the closed position will confirm this fault.

  3. 03

    Loose or Damaged Wiring to LS or INN Terminals

    Wiring / connection

    A disconnected, corroded, or broken wire in the circuit leading to the LS or INN terminals on the control board can cause both inputs to appear open simultaneously. Inspect all wiring connections at the control board and at the switch itself.

  4. 04

    Misaligned Door or Window Switch

    Wiring / connection

    If the switch actuator is not properly aligned with the door or window frame, the switch may not engage fully when the opening is closed. Realigning or repositioning the switch bracket can resolve this without replacing the component.

  5. 05

    Failed Control Board Interlock Circuit

    Part replacement

    In rare cases, the control board itself may have a fault on the LS or INN input circuit, causing it to incorrectly register an open condition. This would typically be suspected only after ruling out all external wiring and switch issues.

See the test procedure for each cause

Frequently asked questions about nP

What does nP mean on a Goodman air_conditioner?
The nP code stands for Window Switch Lockout and appears when the unit detects that both the LS and INN interlock inputs are open at the same time. This signals to the control board that a door or window is open in the conditioned space. The unit suspends all conditioning operations until the circuit is restored to a closed state. Closing the associated door or window is the first and most important step.
How do I fix the nP error on my Goodman air conditioner?
Start by closing all doors and windows that are connected to the unit's interlock circuit, then check whether the error clears on its own. If the code persists, inspect the door or window switch for proper alignment and test its contacts for continuity in the closed position. Also check the wiring at the LS and INN terminals on the control board for loose or damaged connections. If all physical components check out, a technician may need to evaluate the control board itself.
Is the nP error on a Goodman air conditioner a safety hazard?
The nP lockout is not a safety hazard in itself. It is a built-in energy management and efficiency feature designed to stop the unit from conditioning a space when an opening to the outside is detected. The unit simply stops operating until the condition is resolved, which protects both efficiency and equipment longevity. There is no risk of refrigerant leak, electrical danger, or mechanical damage associated with this specific code.
Will resetting my Goodman air conditioner clear the nP error?
A simple power reset will not permanently clear the nP error if the underlying condition, an open door, window, or faulty switch, is still present. The control board will re-enter lockout mode as soon as it detects the open LS and INN inputs again. The error will only clear reliably once the interlock circuit reads as closed, either by physically closing the opening or by repairing the faulty switch or wiring.
How much does it cost to repair a Goodman air conditioner showing the nP error?
If the fix is simply closing a door or window, there is no cost involved. If a door or window switch needs replacement, parts and labor typically range from $75 to $200 depending on the switch type and local labor rates. Wiring repairs can fall in a similar range. If the control board is at fault, replacement costs are generally higher, often ranging from $250 to $600 or more including parts and labor.

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