Code: CH35🔧 LG Mini Split

LG Mini Split CH35 Error Code: Low Pressure Error (Meaning, Causes, Fixes)

Reviewed 2026-10-24 · Based on 2 manufacturer & service sources

What the code means

LG's R410A air conditioner service manual lists error 35 as an excessive pressure drop that "happens because of 3 times successive compressor off due to excessive drop of low pressure by the low pressure sensor." LG's Multi F four-way ceiling cassette service manual titles code 35 "Low Pressure Error" with the cause "Excessive decrease of low pressure." In other words, the system isn't shutting down after a single dip; it has protected the compressor three times in a row and now shows CH35. It is the low-side partner of CH34 (high pressure sensor reading too high) and is different from CH38 (refrigerant leakage detected), which appear in the same LG tables.

Likely causes

Safe DIY checks

⚠ Before you start

Don't open the indoor or outdoor unit or replace internal parts yourself; LG warns this can cause fire, electric shock, serious injury or death. Refrigerant handling requires an EPA-certified technician in the US, and you should never top up a mini split from a DIY can or with a different refrigerant type. Turn off the outdoor unit's breaker or disconnect before anyone works on it.

  1. Turn the system off and clean or replace the indoor unit's air filters. LG names a clogged indoor filter as a cause.
  2. Check the outdoor unit: clear snow, ice, leaves, covers or anything stacked against it, and make sure nothing is blocking the fan.
  3. Make sure the indoor unit's vanes and the airflow in front of it aren't blocked by furniture or curtains.
  4. If the unit was just installed, ask the installer to confirm both outdoor service valves are fully open. LG's flowchart checks this first.
  5. Restore power and run the unit again. If CH35 returns, stop using it and call a licensed HVAC technician or LG service.

🛠 When to call a pro

  • CH35 comes back after the filters and outdoor unit are clear. LG's flowchart moves on to communication cable and piping, refrigerant amount, fans and strainer.
  • Checking the charge and finding the leak. LG says to look for pipe cracks or traces of refrigerant leakage; if a leak is found, it is welded or reconnected and the system recharged; if not, the charge is adjusted.
  • Comparing gauges with the sensor. LG says to check whether the manifold reading and the low pressure sensor value match; if they don't, the pressure sensor is replaced.
  • A clogged strainer. LG says a strainer is suspect when the temperature difference across it is large enough that frost or ice forms at its outlet.
  • If the pressure really is low and the charge, fans and strainer are fine, LG says to check the indoor and outdoor expansion valves, the indoor unit board and the installation conditions.

Parts that commonly fix it

Always match the part number to your exact model.

⚙

Refrigerant leak detector

Used by a technician to pinpoint where refrigerant is escaping before the system is repaired and recharged.

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Replacement air filters

For the indoor unit if the originals are torn or won't come clean; match your LG indoor unit model.

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Outdoor unit main control board

Only after a technician has ruled out charge, valves, fans, strainer and sensor; match the exact LG model number.

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Sources

  1. LG Air Conditioner Service Manual (R410A), error 35 excessive drop of low pressure, main reasons and flowchart (p. 122-123)
  2. LG Multi F Four-Way Ceiling Cassette Service Manual, code 35 Low Pressure Error (via ManualShelf, p. 65)

Last reviewed 2026-10-24. Always confirm against the manual for your exact model number.