TradeAssistIQHome

Mitsubishi Ecodan fault P6

Anti-freeze protection of plate heat exchanger

Heat pump

What it means

Two conditions trigger P6: <Cooling> Ref. liquid temp. (TH2) stays at -5ºC or lower for 10 seconds after compressor operates for 6 minutes; <Defrosting> THW2 detects a temperature ≤15ºC and TH2 detects a temperature ≤-16ºC for consecutive 10 seconds.

Likely causes

  1. Reduced water flow (clogged filter, leakage of water)
  2. Defective water pump
  3. Overcharge of refrigerant
  4. Defective refrigerant circuit (clogs)
  5. Leakage or shortage of refrigerant (Defrosting condition)
  6. Water circulation pump wear leading to pump failure

Where to start

  1. Check water piping for clogged filter or leakage
  2. Check water pump
  3. Check operating condition of refrigerant circuit

The full answer, free

  • 7 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 50), right under the answer
Ask about P6 freeCreate a free account

Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Mitsubishi manual for the Ecodan. Check the model on the data plate before you order parts.

Other Mitsubishi Ecodan fault codes