Climatemaster - Code 3 / Loss of Charge

Article ID: 269
Last updated: 9 May, 2024

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 β€œon” 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/ignored for the initial 60 seconds of a compressor run cycle.

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


1. Check Standing Pressure

  • With the unit off, hook-up refrigerant gauges to the pressure ports in the unit.
    • Blue ⇔ Low Pressure (Suction line connection behind reversing valve)
    • Red ⇔ High Pressure (Discharge line off compressor)
      • Low Standing Pressures = Loss of Charge
        • Be suspicious of a crack in the discharge line elbow 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
      • Tug on the wires going into the spade terminals on the pressure switch (common to have bad/loose factory crimps)

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

This article was:   Helpful | Not helpful
Report an issue
Article ID: 269
Last updated: 9 May, 2024
Revision: 15
Access: Public
Views: 1590
Comments: 0
Also listed in