What Is A P1 Or P4 Error Code? - MRCOOL DIY Ductless Mini Split

A P1 or P4 error code might mean an abnormal rise or drop in the voltage of your MRCOOL system. Or, it may mean you need to release the refrigerant in your MRCOOL unit.

Troubleshooting A P1 or P4 Error Code

When you see a P1 or P4 error code, first turn the unit off. Then turn it back on after two minutes. If the problem persists, go to the outdoor unit. Take off the side wiring cover with a screwdriver. Then, using a multi-meter, test the voltage. For a unit running off of 120 volts, place the ends on L1 and ground. For a unit running off of 240 volts, touch the ends to L1 and L2.

You should also use an Allen wrench to make sure the refrigerant valves are open all the way. It is important you don't force it. Just make sure they are open.

If these steps don't correct the P1 or P4 error code, it's important that you call the MRCOOL Warranty department at 270-366-0457  so they can help you figure out what may be causing the P1 or P4 error code.

Other MrCool DIY Error Codes

  • E0 - Indoor unit EEPROM parameter error
  • E1 - Indoor / outdoor units communication error
  • E2 - Zero-crossing signal detection error
  • E3 - Indoor fan speed has been out of control
  • E4 - Indoor room temperature sensor T1 open circuit or short circuit
  • E5 - Evaporator coil temperature sensor T2 open circuit or short circuit EC - Refrigerant leakage detection
  • F0 - Overload current protection
  • F1 - Outdoor ambient temperature sensor T4 open circuit or short circuit
  • F2 - Condenser coil temperature sensor T3 open circuit or short circuit
  • F3 - Compressor discharge temperature sensor TP open circuit or short circuit
  • F4 - Outdoor unit EEPROM parameter error
  • F5 - Outdoor fan speed has been out of control
  • P0 - IPM malfunction or IGBT over-strong current protection
  • P1 - Over voltage or over low voltage protection
  • P2 - High temperature protection of IPM module or compressor top
  • P3 - Outdoor ambient temperature too low
  • P4 - Inverter compressor drive error
  • P5 - Indoor units mode conflict (multi-zone ONLY)
  • P6 - Low pressure protection(Only for 36K)
3 comments (view/add)
  • Tony Esposito
    Tony Esposito
    Posted on 6/7/2019

    My unit was installed by a certified HVAC TECH. I know nothing about how to test the electrical nor do I own a electrical testing meter.

    The only thing I can do is call the installer to come out and do your recommended testing. So who is going to pay the installer?

  • Kyle
    Kyle from Ingrams
    Posted on 6/7/2019

    If your unit was installed by a certified HVAC Tech and you have a problem, you should contact the tech. Virtually all techs warranty their own installation work.

  • Joseph Fiorella
    Joseph Fiorella
    Posted on 8/20/2019

    i had a p1 error code. turns out the 12k advantage unit is 220v, unlike the DIY 12k unit which is 110v. All of my ductless mini splits are working perfect now :)


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