Midea Heat pump fault P4

What it means

Protects the compressor from abnormally high discharge temperatures and transient spikes. Triggered when discharge temperature rises above 115°C.

Likely causes

1. Abnormally high discharge temperature
2. Transient temperature spikes in the compressor discharge line
3. Low ambient temperature (T4<3°C) combined with low water-side temperature triggers freeze protection
4. Water side temperature dropping below critical thresholds due to low flow, low ambient temperature, or system stoppage
5. Abnormal state detected requiring compressor protection
6. Set temperature reached (normal stop)
7. Damage to cables
8. Excessive number of connections
9. Terminals not made to original specification
10. Damage to seals
11. Incorrect fitting of glands
12. Abnormal system state detected

Where to start

1. Monitor discharge temperature (Tp) and suction temperature (Th) during compressor operation
2. Track compressor running time against 12 minute threshold for EA logic
3. Measure discharge temperature and compare to 115°C threshold