What is an E1 Error Code? - MRCOOL DIY Ductless Mini Split

If an E1 error code shows up in your air handler, that means there is a communication error either with the indoor unit or the outdoor unit. The causes for this could be a wiring mistake, or a faulty control board with the indoor unit or the outdoor unit.

Troubleshooting An E1 Error Code

One thing you can do to try and troubleshoot the E1 error code is power off the MRCOOL DIY mini split then wait two minutes and restart it. If the E1 error code displays again, however, you may want to measure the unit's voltage. If you are not comfortable working with electricity, you may want to call MrCool tech support at 270-366-0457.

For the outdoor unit, take off the side wiring cover with a screw driver. Then, using a multi-meter, test the voltage. For a unit running off of 120 volts, touch the ends to L1 and Ground. For a unit running off of 240 volts, you will want to touch the ends to L1 and L2.

For the indoor unit, you will want to place the ends of the multi-meter on 1 and 2 to make sure the unit is getting voltage. For a 120 volt unit, you will want to go between 1 and Ground. Doing these things will help you determine if the unit is wired correctly. If it is not a wiring issue, it is possible your control board may need to be replaced in either the indoor unit or the outdoor unit.

This is when it is important to call the MRCOOL Warranty Department so they can help you determine the reason for the E1 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)
20 comments (view/add)
  • Tony
    Posted on 8/7/2022

    What is the small button you can press on the control board?

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 8/18/2022

    This button reconfigures the line sets and electrical automatically in case there was an installation issue.

  • Tony
    Posted on 8/7/2022

    We have 36k Mr Cool condenser with 4 air handlers. We got a P4 error on all 4 air handlers. Ingraham tech said it must be the warrantied control board. We switched out the control boards. Now we get E1 error message. Turned off units for 2 minutes, turned them back on same error code E1. Checked L1L2 240 volts AC and needle was steady on 240. Checked A,B,and C and all were steady on 240 Volts AC. Error code E1. No cool air. new control board.

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 8/18/2022

    Please give us a call at 270-575-9595 as soon as you possibly can.

  • Jason Ross
    Jason Ross
    Posted on 4/17/2022

    I just installed the DIY 27k multi unit with 9k & 12k indoor units. I had just finished running the initial test and I got a P6 error code on both indoor units I can't find any information on how to correct it on a 27k unit what does a P6 error code mean

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 4/20/2022

    Please give us a call at 270-575-9595, or contact the manufacturer.

  • Jordyn Dietzler
    Jordyn Dietzler
    Posted on 1/8/2022

    I have a minisplit with 2 indoor units, I Installed June 6th 2021. I had both heat and ac wotking just fine. But now that it's winter I hadn't had it on in a few months. I woke up one morning and both indoor units had an E1 code. I reset the breaker a few times and waited 10 minutes. And E1 keeps showing up.

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 1/10/2022

    That error code is indicative of a communication error between the indoor and outdoor units. Please give us a call at 270-575-9595 so that our tech support team can assist you.

  • Mike Main
    Mike Main
    Posted on 11/2/2021

    Purchased 3 Mr Cool systems outdoor M# DIY-Multi3-27HP230, 2 installed, one installed mid September second installed mid October, 2021 for both units, on Sunday one unit had error code P1 reset by turning off then on power, worked fine, today I’m showing E1, full power to both indoor and outdoor units.
    Did everything in the trouble shooting guide, pushed the black button for digital light, but it never came on.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 11/4/2021

    Give us a call at 270-575-9595 and speak with tech support.

  • Paul Yuccas
    Paul Yuccas
    Posted on 10/28/2021

    Interested in a response to David’s comment earlier. I am having the same issue.

  • David
    Posted on 5/27/2021

    Have a dual ductless MRCOOL. Less than a year old. Tested voltage where specified. Reset CB for 5mins. Both units will work after resetting but will go back to E1 after a while, sometimes half a day or just a few minutes.MULTI2-18HP230V1, Outside unit. O-MULTI12HP-WMAH-230 inside unit.

  • Adam
    Posted on 4/12/2021

    I installed ducted eco air ac unit and got a E-1 error code. I checked my wire between outdoor and indoor unit and I have continuity and also I got proper voltage. I changed thermostat and checked all connections and fuses. Indoor fan works fine but no cooling. Please help

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 4/13/2021

    I'm sorry, but we don't carry Eco Aire and we're not that familiar with it. The owner's manual should have a troubleshooting section that might help.

  • ken
    Posted on 9/15/2020

    How do I determine witch control board it is for e1 code

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 9/15/2020

    This requires a voltmeter set to the DC scale. The probes are used on terminals 2 and 3 at the outdoor unit with the system turned on. If the DC voltage is a fixed value, the indoor board is the problem. If the DC voltage is a varying valve and does not change polarity, then the outdoor board is the problem.

  • Bev
    Posted on 7/27/2020

    On really cold mornings the display is E1 .And I haven't even touched anything.Stays like that till the sun comes up .It comes on when it gets warmer.Meanwhile I freeze.Had a person come round saud he couldn't find anything wrong with it.Still charged $137.00 Unit is 13yrs old and a Gujjar.Should I replace it.Goes fine normally.

  • Steven
    Steven from Ingrams
    Posted on 7/28/2020

    We've never heard of a Gujjar air conditioning system. If you paid an HVAC technician to diagnose the problem and they couldn't find anything wrong, but there is evidently something wrong, then I would suggest you get a second opinion from a different HVAC technician. The entire system may need replacing, or it may be a fairly simple fix to continue with the current system.

  • David Bonzell
    David Bonzell
    Posted on 7/30/2019

    I have a DA2421-H21 24,000 btu Ductless Air unit. Once a week I notice error code P4 at the Display window and a hissing of R410A inside the evap unit coils. This continues for 15 seconds, and the code and hissing clears. Can you reply on the cause?

  • Steven
    Steven from Ingrams
    Posted on 7/31/2019

    We don't sell the DuctlessAire line of mini-splits, so we wouldn't know for sure what the issue may be. However, if it were the MrCool DIY line of mini-splits, this video may help: https://iwae.com/resources/videos/p1-p4-error-code-mrcool-diy-ductless-mini-split.html

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