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)
15 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 :)

  • Debbie
    Posted on 9/8/2019

    What is a P7 error code. Our wifi mini split worked great and then kept showing offline, which meant no control of it through the app. I installed a new wifi kit and it worked for two months. Now I am back to Offline. Shortly after I get it to the AP mode, it displays P7 and the network is not displaying in my app. Any suggestions?

  • Kyle
    Kyle from Ingrams
    Posted on 9/9/2019

    I'm not familiar with a P7 error code. Please give us a call at 270-575-9595 x300 to speak to the Tech Department.

  • Russell Ehrlich
    Russell Ehrlich
    Posted on 11/3/2019

    I have a P2 code on the heating cycle and the unit stopped. What needs to be done to correct this issue? I purchased the premier unit.

  • Kyle
    Kyle from Ingrams
    Posted on 11/4/2019

    Give us a call at 270-575-9595 and use extension 300 for the Warranty & Tech Department.

  • Greg
    Posted on 11/11/2019

    I have a new Mr Cool we had a blinking 88 and a data sign we replaced the inside blower motor it is doing the same thing again. What can the issue be

  • Kyle
    Kyle from Ingrams
    Posted on 11/12/2019

    The 88 flash is usually from mis-wiring – particularly between the indoor and outdoor units. If the unit was just installed, then we would suggest checking to see that terminal 1 indoors is wired to terminal 1 outdoors, 2 to 2, etc. If the unit has been operating for some time, then we would suspect the fan motor or the indoor control board.

  • Cory
    Posted on 11/22/2019

    Installed a triple head Mr.Cool 6 months ago. P6 coming up all of a sudden on one unit only?

  • Kyle
    Kyle from Ingrams
    Posted on 11/22/2019

    A P6 indoors indicates a system pressure problem, either high or low. You need a tech must look at the outdoor control board to determine which one it is.

  • Zowie
    Posted on 12/28/2019

    Hi i am getting p4 error on my midea fp-51ara010heiv-n4 is this something i can fix on my own or should i need a repair?

  • Kyle
    Kyle from Ingrams
    Posted on 12/30/2019

    That particular Midea window air conditioner is not a unit that we carry. We're not sure what a P4 error code on that unit indicates.

  • Ron
    Posted on 1/2/2020

    I installed the double head Mr cool unit four months ago. It has been working good in ac mood. Now it is getting cool and when the unit goes to heat mode a P0 code will start to flash as the unit satisfied and is winding down. It will start over with out doing nothing and will blow warm air until it satisfied and starts wind down and flashes the P0 agin.

  • Kyle
    Kyle from Ingrams
    Posted on 1/3/2020

    Give us a call at 270-366-0457 to speak with tech support

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