Slight temperature difference between indoor room temperature and pipe temperature thermistor
Mitsubishi Electric · Mitsubishi PUZ-HA30-36NHA4 Outdoor Unit
What does P8 mean?
The P8 abnormality is detected when there is an insufficient temperature difference between the indoor room temperature (TH1) and the indoor pipe temperature (TH or TH) during cooling or heating operation. In cooling mode, the pipe temperature must be within the cooling range (TH_pipe - TH1 < -3°C) after 9 minutes. In heating mode, the condenser/evaporator pipe temperature (TH) must be within the heating range (TH_pipe - TH1 > 3°C) after 17 minutes. Potential root causes include refrigerant shortage, disconnected thermistor holder, defective refrigerant circuit, converse connection of extension pipes, or incomplete opening of stop valves.
Additional Steps
Steps 1–2 are listed in Priority Fix.
- 3
Inspect the stop valve to ensure it is completely opened.
- 4
Check for refrigerant shortage or leakage in the refrigerant circuit.