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H4: System Overload, High Temperature Resistance Protection


Safety Note: Before any component is electrically disconnected in the unit, shut off main power. Inverter board DC bus voltage can take up to 15 min to discharge.

Caution: Do not plug or unplug components while electrical power is present, this can damage the equipment and control boards.

Step 1: Check the Outdoor Ambient Hi/Low

  • Measure the outdoor ambient temperature and ensure it is within the acceptable operating range.


Step 2: Check for Dirty Filters, Coils

  • Inspect and clean the indoor filters, coils, and blower wheel. Dirty components can lead to reduced efficiency and overheating.


Step 3: Check for Blocked Air Flow

  • Ensure there are no obstructions or blockages in the airflow path. Confirm that the indoor and outdoor units have adequate space for proper airflow.


Step 4: Check if System Undercharged

  • Verify the refrigerant charge level. If the system is undercharged, it can lead to overheating. Follow proper procedures for checking and adjusting the refrigerant charge.


Step 5: Check for Restriction

  • Investigate for any restrictions in the refrigerant lines, expansion valve, or other components. A restricted system can contribute to increased temperatures.


Step 6: Check by 4 Point Temp Check

  • Perform a 4-point temperature check to assess temperature differentials across various components. This can help identify specific areas contributing to the system overload.

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