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ICP · Heat pump

2 System pressure trip

High severity ICP N4H3 Heat Pump

What the control is telling you

Discharge or suction pressure out of limits, or compressor overloaded.

Applies to: ICP N4H3 R-410A split heat pump (manual 428 01 5103 02); Comfort Alert codes apply only to units factory-fitted with the Comfort Alert module

Likely causes

  • High head pressure
  • Poor outdoor coil airflow (dirty, blocked, damaged)
  • Outdoor fan not running
  • Return duct leaking badly
  • Low pressure switch open (if fitted) - see Flash Code 1

Test and repair steps

  1. Clean the outdoor coil and clear anything within 18 in. of the coil inlets.
  2. Check the outdoor fan runs (motor, capacitor, wiring).
  3. Check return duct for large leaks.
  4. Check head pressure and refrigerant charge.
  5. If a low pressure switch is fitted, follow Flash Code 1 checks.

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Source: ICP N4H3 Installation Instructions 428 01 5103 02, Comfort Alert Diagnostics Codes (Figure 18), p.20. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.