Carrier H5

What does Carrier H5 mean?

Carrier's IPM (intelligent power module) protection has engaged. The manual lists the causes as IPM module over-temperature, low voltage, or a silica grease problem. The power module drives the compressor, so the control shuts the system down to protect it when the module reports a fault condition.

Symptoms

• H5 shown on the indoor unit display
• Compressor will not run
• Code can follow voltage problems or overheating
• Fault tied to the outdoor power module

Common causes

• IPM module over-temperature
• Low supply voltage
• Silica (thermal) grease problem on the module
• Inadequate heat transfer from the power module

Diagnostic steps

1. 01

   Confirm the H5 code

   Verify H5 on the indoor unit display, which reports faults for both units.

2. 02

   Check supply voltage

   Since low voltage is a listed cause, confirm the incoming voltage is adequate.

3. 03

   Check module temperature and mounting

   Per the manual, consider IPM over-temperature and the silica grease interface on the module.

4. 04

   Correct the cause and retest

   Address voltage, cooling, or thermal-grease issues, then confirm H5 clears.

When to call a professional

The intelligent power module is a high-voltage inverter component, and faults involving over-temperature, voltage, and thermal grease should be diagnosed by a licensed HVAC technician. Working on the inverter board carries shock risk and requires correct thermal-interface handling. Have a qualified professional confirm the IPM diagnosis and perform any module or board service.