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Error code reference

Goodman Air Conditioner Error Code FP

Freeze Protection Engaged

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Freeze Protection Engaged - the room temperature measured by the wireless remote thermostat or indoor ambient thermistor active sensor falls below 40°F.

First step from the service manual

No action required. This setting will disengage when the room temperature rises above 43°F.

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

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What FP means on a Goodman air conditioner

The FP code on a Goodman air conditioner indicates that the Freeze Protection feature has been activated. This occurs when the room temperature detected by either the wireless remote thermostat or the indoor ambient thermistor sensor drops below 40°F. At this threshold, the system automatically suspends normal cooling or heating operation to prevent potential equipment damage and to protect the living space from excessively cold conditions. The FP code is a protective state, not a fault or malfunction in the traditional sense.

The indoor ambient thermistor is a negative temperature coefficient (NTC) resistive sensor that continuously monitors room temperature and feeds that data to the main control board. When its reading falls to or below 40°F, the control logic engages freeze protection mode and halts operation. The system remains in this state until the ambient temperature climbs back above 43°F, at which point the protection automatically disengages and normal operation resumes. This 3°F hysteresis band prevents the system from rapidly cycling in and out of freeze protection mode.

In most cases, the FP code appears during unusually cold ambient conditions, such as a unit operating in an unheated space during winter months, a room with an open window or door in cold weather, or a scenario where the space has been cooled excessively. Sensor faults are a secondary consideration. If the room is genuinely cold, no intervention is needed. If the space should be warm but the code persists, the thermistor or wireless remote thermostat may need evaluation.

Source: manufacturer service documentation.

Common causes of FP

  1. 01

    Genuinely cold ambient room temperature

    Wiring / connection

    The most common trigger is real-world cold air in the space, such as an open window, door, or an unheated room during winter. Confirm actual room temperature with a separate thermometer to rule this out first.

  2. 02

    Unit operating in an unconditioned or outdoor-adjacent space

    Wiring / connection

    Mini-split or window units installed in garages, sunrooms, or other spaces without adequate insulation can see ambient temperatures drop below 40°F during cold weather, legitimately triggering the protection.

  3. 03

    Wireless remote thermostat positioned near a cold draft

    Wiring / connection

    If the wireless remote thermostat is placed near an exterior wall, vent, or window, it may read a colder temperature than the actual room average, causing a false FP trigger. Relocating the remote thermostat to a more central position can resolve this.

  4. 04

    Faulty indoor ambient thermistor

    Part replacement

    A thermistor that has drifted out of calibration or developed an open circuit can report falsely low temperatures to the control board. Resistance values should be measured and compared to the expected NTC curve for the specific sensor to confirm a fault.

  5. 05

    Weak or failing wireless remote thermostat battery

    Part replacement

    A low battery in the wireless remote thermostat can cause erratic or incorrect temperature readings, potentially triggering freeze protection when the room is not actually cold. Replacing the battery is a quick first check if the remote is acting as the active sensor.

See the test procedure for each cause

Frequently asked questions about FP

What does FP mean on a Goodman air_conditioner?
FP stands for Freeze Protection Engaged. It means the system detected a room temperature at or below 40°F via the wireless remote thermostat or the indoor ambient thermistor sensor. The unit suspends operation automatically to protect itself and the space. Normal operation resumes automatically once the room temperature rises above 43°F.
How do I fix the FP code on my Goodman air conditioner?
In most cases, no manual fix is required. The FP code will clear on its own when the room temperature climbs above 43°F. If the code appears repeatedly and the room is not actually cold, check the placement of the wireless remote thermostat for drafts and inspect the indoor ambient thermistor for resistance faults. Correcting the temperature sensor location or replacing a faulty thermistor typically resolves recurring false triggers.
Will resetting the unit clear the FP code on a Goodman air conditioner?
A manual reset will not permanently resolve the FP code if the underlying condition, which is a room temperature below 40°F as read by the sensor, still exists. The code will reappear as soon as the system checks the ambient temperature again. The condition must clear naturally or the sensor issue must be corrected before the code will stay off.
Is the FP code on a Goodman air conditioner a safety concern?
The FP code itself is a safety and protection feature, not an indication of a dangerous fault. The system is working as designed by halting operation in very cold conditions. However, if the code is appearing falsely due to a bad thermistor or misplaced remote thermostat, the unit may be unnecessarily preventing heating or cooling. Addressing the root cause ensures the system operates correctly when needed.
How much does it cost to repair the FP error on a Goodman air conditioner?
If the FP code is triggered by actual cold room temperatures, there is no repair cost since the system resolves itself. If the cause is a faulty indoor ambient thermistor, replacement parts typically range from $15 to $60 depending on the model, with professional labor adding $75 to $200 or more. Repositioning a wireless remote thermostat to avoid drafts is a no-cost fix you can do yourself.

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