Climatemaster - Code 3 / Loss of Charge

Article ID: 269
Last updated: 08 Feb, 2023

Climatemaster Geothermal: Heating / Cooling

Re: Code 3 / Loss of Charge

Code 3 = Low Pressure Fault

The low pressure switch must be open and remain open for 30 continuous seconds during an “on” cycle to be recognized as a low pressure fault.

If the low pressure switch is open for 30 seconds prior to compressor power up it will be considered a low pressure (loss of charge) fault.

  • The low pressure switch input is bypassed for the initial 60 seconds of a compressor run cycle.

Qty Possible Causes:
2 Low Refrigerant Charge
Bad Expansion Valve
Bad Pressure Switch
1 Loose/Broken Pressure Switch Terminal


1. Check Standing Pressure

  • With the unit off, hook-up refrigerant gauges to the pressure ports in the unit.
    • Blue --> Low Pressure
    • Red --> High Pressure
      • Low pressures = Loss of Charge
        • Be suspicious of a crack in the discharge line 90 leaving the compressor.

2. Check Operation

  • Set the thermostat to call for cooling.
  • If the heat pump is in lockout, reset by removing 24VAC power to the control board.
    • Good Pressure + Unit goes into Low Pressure lockout before the compressor tries to start = Bad Pressure Switch or Loose/Broken Terminal

3. Check Operating Pressures

  • Once the compressor starts, monitor system pressures.
    • Suction pressure goes very low or into a vacuum in first 60 sec = Bad Expansion Valve

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Article ID: 269
Last updated: 08 Feb, 2023
Revision: 13
Views: 1148
Comments: 0
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