Components

Inverter module

The power electronics that vary compressor speed, also called the IPM or intelligent power module. An inverter-module protection code means the module measured current, voltage, or temperature outside limits and stopped before damage occurred.

Also called IPM, inverter board, power module

Direct answer

What is an inverter module?

An inverter module, or IPM, is the power electronics stage that varies compressor speed. It monitors its own current, voltage, and temperature and stops the compressor when any of them exceeds a limit.

Inverter module: how it works

The module rectifies the incoming supply and then switches it back out at whatever frequency the board asks for, which is how compressor speed is varied. Doing that generates heat in the switching devices, so the module carries a heat sink and its own protection: when current, supply voltage, or its own temperature moves outside limits, it stops rather than damage itself.

Where you meet the term

  • In an IPM or module protection code, where the module stopped the compressor at a limit.
  • In a fault that appears only on hot days, where module temperature rather than the compressor is what reached its ceiling.
  • In a supply voltage complaint, where an unstable or low incoming supply triggers protection at the module.

How to check it

  1. Record outdoor temperature and how long the unit had run. Module protection that appears after twenty minutes on a hot afternoon points somewhere different from protection at start-up on a cool morning. Owner check
  2. Clear the outdoor unit and its discharge path. The module heat sink is cooled by the same airflow the condenser uses, so restricted air raises module temperature as well as head pressure. Owner check
  3. Measure supply voltage under load. A supply that sags when the compressor starts can trigger module protection while reading correctly at rest. Technician
Read this twice

Inverter module: what it is not

  • An IPM code does not mean the module is faulty. It records that the module reached a protection limit, and the reason for that limit can sit outside the module entirely.
  • Repeatedly clearing the code does not address the condition. If it returns under the same conditions, the conditions are the finding.

Inverter module questions

What causes IPM protection?

Anything that pushes current, supply voltage, or module temperature outside limits. Restricted outdoor airflow, a compressor drawing more than it should, and an unstable electrical supply all reach the same protection.

Is the inverter module the same as the control board?

No. The control board makes decisions and the inverter module handles the power. Some units combine them on one assembly, which is why the manual for the model matters when ordering parts.

Why does the fault only happen in hot weather?

Module temperature protection is directly tied to how well the heat sink can shed heat, and that depends on outdoor air temperature and on airflow through the unit. Cool weather may keep it just inside the limit.

Where this definition comes from

Written from manufacturer support article material held in the HVAC Bench evidence record. Where a document limits a definition to certain models, that limit is repeated here rather than generalised across a brand.

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