System Diagnosis
Model Plug Missing. Model plug is not presently installed on the PCM or was not present when power was applied; equipment can still operate if a valid value is stored in memory.
Carrier Heat Pumps
Error Code 25-22
Troubleshooting guide for the Carrier Heat Pumps system fault 25-22.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
Potential Causes & Solutions
- Install the correct model plug for this unit on the PCM.
- Verify model plug part number matches the unit model.
- Equipment may continue to operate from stored memory but install correct plug to clear fault.
Verify Before Replacing Parts
- Confirm the exact Carrier model family and heat pumps context before acting on a generic code description.
- Verify current draw, overload status, and control signal before condemning the compressor or drive.
- Look for upstream conditions such as airflow or charge issues that may be pushing the compressor into protection.
- After the correction, run the system long enough to confirm the code does not return under normal load.
Field Signals to Confirm
What usually confirms it
Protection trips that line up with abnormal current draw, temperature, or drive behavior.
What can fool you
Upstream airflow or refrigerant issues can push the compressor into protection even when the compressor is healthy.
When to Escalate the Call
- The compressor or drive shows repeat protection events under normal load.
- You cannot separate compressor health from upstream system issues with confidence.
Still unsure about this fault?
ACLogics walks you through Carrier Heat Pumps diagnostics step-by-step — so you confirm the cause before swapping parts.
