01 Low side fault or low pressure switch trip

What the control is telling you

Code 01 covers two low-side events: (1) four compressor protector trips in a row with an average run time over 3 hours between trips (very long runs, compressor on high with fan on low); (2) the low pressure switch has opened - compressor and outdoor fan are off while the thermostat still calls.

Applies to: Communicating 2-stage condensers and heat pumps with the PCBHR104 or PCBHR105 outdoor control (7-segment display): ASXC16/18, GSXC16/18, DSXC16/18, ASZC16/18, GSZC16/18, DSZC16/18

Likely causes

• Low refrigerant charge
• Restricted liquid line (drier, kinked line)
• Indoor blower motor failed or not running
• Thermostat set very low
• Faulty low pressure switch (switch-trip version)

Test and repair steps

1. Warning: Kill power to the outdoor unit before touching wiring, the compressor terminals or the control.
2. Check charge with superheat/subcooling and correct it; leak check if low.
3. Look for a temperature drop across the liquid line drier or any kinks - repair restrictions.
4. Confirm the indoor blower runs at the right speed and filters/coil are clean.
5. Check the thermostat set point.
6. Test the low pressure switch it should open at about 21 psig and reset near 50 psig; replace if it does not.
7. Low side fault version clears after 30 normal cycles in a row, or by power cycling the 24 VAC to the control.

Models that show this code

24 models in Goodman/Amana ComfortNet ASZC/GSZC/DSZC

Other codes on the same units

• 02 High side fault or high pressure switch trip
• 03 Short cycling
• 04 Locked rotor
• 05 Open circuit - compressor off over 4 hours
• 06 Open start circuit
• 07 Open run circuit
• 08 No line voltage
• 09 Low 24 V control voltage