CH32 on a LG heat pump: High discharge-pipe temperature of the inverter compressor – compressor switched off
Short answer
On a LG heat pump, CH32 means: High discharge-pipe temperature of the inverter compressor – compressor switched off. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the LG, all models
The manual says: High discharge-pipe temperature of the inverter compressor – compressor switched off.
Part involved: compressor discharge / refrigerant charge.
When it shows: Discharge temperature rises above limit.
Likely causes:
- Overload operation (outdoor fan restrained, shielded, clogged); refrigerant leakage or shortage; discharge temperature sensor defective; EEV/LEV connector displaced or poor EEV assembly.
On the THERMA V Water Heater (heat pump DHW cylinder)
The manual says: Discharge pipe is overheated (105 °C) (THERMA V water heater).
Part involved: refrigerant circuit.
When it shows: Discharge pipe is overheated (105 °C).
Likely causes:
- Discharge pipe is overheated (105 °C).
Is it safe?
On the LG, all models
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: yes – trouble clears when the condition is repaired; emergency operation must be restarted by the user after a power reset.
Manual reset: Not normally required; user restarts after power reset if emergency operation was running.
On the THERMA V Water Heater (heat pump DHW cylinder)
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: unknown.
Manual reset: Per LG corrective action; service engineer for most codes.
What you can check
On the LG, all models
- Read the code on the controller (LG shows 'CH' + number; older wired controllers alternate 'CH' and the number) and note it together with the model number. Report it to your installer or an LG-authorised service centre – LG owner's manuals say an error code generated by self-diagnosis is a reason to call the service. For this 'trouble' class LG allows temporary emergency operation: if the controller shows a pop-up offering it you may accept (OK) as a stop-gap; running costs will be higher, so do not use it long term. Emergency operation does not restart by itself after a power cut – you must switch it back on at the controller. Check (without opening any panels) that the outdoor unit is not blocked by leaves, debris, snow or ice and that nothing is stacked against the coil or fan grille.
On the THERMA V Water Heater (heat pump DHW cylinder)
- Note the code shown on the water heater display. LG's corrective action: call LG technical support. While the fault is present the unit operates as: Use elements only – hot water will be heated more slowly/at higher cost.
What the engineer will check
On the LG, all models
- Check outdoor fan, clearances and coil, pipe bends; discharge sensor (CN_DISCHARGE, ~200 kΩ at 25 °C); EEV connector/operation; leak test and correct refrigerant charge.
Who to ask for: Heat pump engineer with LG Therma V training; F-gas certified refrigeration engineer for refrigerant-circuit work.
Certification: F-gas certification (UK F-gas Regulation, Category I) for any refrigerant handling on R32/R410A units; for R290 units additionally competence in flammable (hydrocarbon) refrigerants (e.g. BESA/ACRIB HC safe handling).
On the THERMA V Water Heater (heat pump DHW cylinder)
- Check air path/filter, fan, EEV, refrigerant charge (F-gas/R134a or unit refrigerant per data plate), sensors.
Who to ask for: Heat pump engineer with LG Therma V training; F-gas certified refrigeration engineer for refrigerant-circuit work.
Certification: F-gas certification (UK F-gas Regulation, Category I) for any refrigerant handling on R32/R410A units; for R290 units additionally competence in flammable (hydrocarbon) refrigerants (e.g. BESA/ACRIB HC safe handling).
What you might notice
Sources
- AIR-TO-WATER HEAT PUMP SERVICE MANUAL (General) – R32 Hydrosplit, MFL68682007 ↗ · MFL68682007 · page 72, 113 · Reviewed 23 September 2026
- LG Heat Pump Water Heater Owner's Manual WH20S F5 / WH27S F5 (EU/UK multilingual), MFL71409209 Rev.00 (2023) – ManualsLib 3195149 ↗ · MFL71409209 Rev.00_090823 · page 32 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026