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)
66 comments (view/add)
  • Chris
    Chris
    Posted on 5/14/2022

    I just hooked up my 36K 4 zone DIY and when I turned the unit on the first time I got P6 errors on each indoor unit and the outdoor LED board displayed P2. Not sure what the problem is here?

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 5/18/2022

    A P6 error code indicates a discharge temp sensor error. A P2 error code is high temperature protection of compressor top diagnosis and solution. Please give us a call at 270-575-9595.

  • Steve cook
    Steve cook
    Posted on 5/12/2022

    I have a diy-hp-24 Mr cool and the control board on the indoor has no display.The unit will not respond to the remote if I try to power on.I tried replacing batteries and tried a new remote.If I push the force button on the unit the board displays temp and the fan comes on. But the remote will not turn unit on and display blank unless I force cool button

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 5/18/2022

    Please give us a call at 270-575-9595.

  • Nico
    Nico
    Posted on 4/24/2022

    I have a 36k multi unit mr cool system. Im getting a p6 on all three air handlers and i took cover off of condenser outside and that is showing a p1 code. Also when i turn the mode to heat on all three air handlers nothing happens no air flow at all? What could yhe problem be?

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 4/27/2022

    A P6 error code indicates a discharge temp sensor error. Please call us at 270-575-9595, or contact the manufacturer.

  • Phil
    Phil
    Posted on 4/19/2022

    How do I troubleshoot a F3 error code on a MRCool DIY 3 zone with 2 air handlers installed? Only one of the air handlers displays the error, but neither zone works.

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

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

  • Thomas Edward Kelley
    Thomas Edward Kelley
    Posted on 3/30/2022

    I get no heat from my mr cool split unit i get a error code p4 what should i do, the voltage to the unit is fine

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 3/31/2022

    Please give us a call at 270-575-9595.

  • Nick
    Nick
    Posted on 2/12/2022

    Your site says that the P6 error code is for the 36K Units only but I have a 27K unit throwing that code. Any ideas?

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 2/14/2022

    That code indicates a discharge temp sensor error. Please give us a call at 270-575-9595.

  • Jonathan Ladner
    Jonathan Ladner
    Posted on 12/31/2021

    We purchased the 12000 BTU 19.5 SEER in July 2020, the outdoor unit is coming on running approximately 30 seconds and giving a P4 error. The unit has been turned off as instructed in the video, L1 and L2 has 118 volts on both.

  • Rebekah Muller
    Rebekah Muller from Ingrams
    Posted on 1/3/2022

    Please give us a call at 270-575-9595 so that you can get in contact with tech support.

  • James Page
    James Page
    Posted on 11/5/2021

    I installed m second 12000 btu DIY unit. This unit powers through in cool mode(turbo works) but heat gives a p4 error(turbo doesn’t power on). I checked no leakage and wired right.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 11/8/2021

    Call us at 270-575-9595 and speak with tech.

  • Josiah
    Josiah
    Posted on 8/30/2021

    I have a 240V DIY 24k Mr Cool unit that has run for 2 years without an issue. I had to clean the drain line (indoor water leak) and correct a mounting issue with the indoor unit and then it would not turn on. No error codes or anything. After chatting with Mr Cool and doing some troubleshooting, I first replaced the indoor control board, and then the outdoor control board after that didn't work. I have also tried a new cable despite good continuity checks between the indoor and outdoor units to no avail. Supply voltage is present on both units.

    On the indoor board (new and old), The low voltage 5VDC doesn't show up at all with a meter which is why I assume the LED board isn't lighting up. Nothing seems visibly cooked on either of the boards boards. The new indoor board was replaced before I also replaced the outdoor board. Using the micro switch on the board did nothing as well.

    With the outdoor board, I'm getting a steady green light and a slow, then fast blinking yellow/orange light which I have only deduced likely means error. I hear a click from a relay or valve kick in when the outdoor unit is turned on but that is it. It then clicks again after power off and the caps drain out.

    I'm at a loss with it. I was sent to you guys for the replacement boards that I got by Mr Cool and Mr Cool has tried to help on the phone to no avail. I saw this Q and A and figured I would ask in case one of you guys have seen this or have any ideas on what could be going on. Would

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 9/1/2021

    What you describe sounds like either a wiring issue or an indoor board problem. It is unusual for a replacement board to be bad but it is possible. I would first check the DC voltage at the outdoor unit at terminals 2 and 3. With the unit on it will be either a fixed voltage or a varying voltage that does not change polarity. Fixed voltage is a bad indoor board, varying with no polarity change is a bad outdoor board. You may be able to get MrCool to order another indoor to board for you to try or you could contact an HVAC technician to come do a service call to diagnose the unit.

  • Jordan Chiow
    Jordan Chiow
    Posted on 7/27/2021

    New 24k BTU 20 SEER MrCool DIY Ductless Heat Pump Split System 3rd Generation installed and it keeps running for a short time then giving an Error of P4. Would low Freon cause this error code?

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 7/28/2021

    P4 indicates an abnormal rise or drop in voltage. Give our tech department a call at 270-575-9595 x300.

  • Han
    Han
    Posted on 6/13/2021

    My unit reads PO I have turned breaker off for several minutes trying to reset it doesn't change anything.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 6/14/2021

    Call us at 270-575-9595 x300 for tech support.

  • Andres
    Andres
    Posted on 4/18/2021

    Looks like Mr Cool and Senville have the same error coding? Just installed a Senville 18000 BTU Dual Zone. Outdoor unit shows error code E5 and indoor units P1. According to Senville code list. E5 is Voltage problem and P1 is abnormal voltage. I guess it’s the same issue being registered indoor and outdoor?

  • Justin Manley
    Justin Manley
    Posted on 4/8/2021

    We installed a 12,000 btu mr cool system and when we turned it on we received a P1 error code. We turned off the system and turned it back on and while opening the head unit door that rotates upward the led turned off. We have been unable to get it to power on after that. Any ideas what may be wrong? (we already checked the led box and led control cable with another unit.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 4/10/2021

    The display module on the back side of the lid has a cable connection to the board. That cable must be connected for the unit to work.

  • input. Cubie
    input. Cubie
    Posted on 2/17/2021

    Thank you Kyle for the message, installer came out checked unit and determined the actual code was P3 due to -35° wind chill in our area overnight. Built a wind break for future problems. Working Great now really appreciate your imput.

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 2/17/2021

    Glad it worked out! And -35° is harsh.

  • Bruce Cubie
    Bruce Cubie
    Posted on 2/16/2021

    I have Klimaire mini split model KSIV012-H119-O it was installed 2-19-2020 and in the heat mode it just threw a P1 code. What do I do

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 2/16/2021

    The Klimaire KSIV service manual indicates that a P1 code indicates a voltage problem. Either it is over voltage or too low voltage. You should probably have the installing technician come out to evaluate the unit.

  • Chris
    Chris
    Posted on 1/26/2021

    MrCool 36K, been running perfect and nearly non-stop since April. For the past month I've been getting an F0 error and no heat once the temp dips below 50F. Outside unit sounds like everything is going to work until the the moment the pump kicks on, then it immediately shuts back down. The fan remains running for 30-45 seconds. In AC mode, low side pressure reads 118-119 PSI.

    The unit keeps cycling through this process, I'm guessing every 5 minutes.

    Given these variables, what could throw the F0 error?

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 1/27/2021

    It can be a number of things. I would first try to add a small amount of refrigerant to get the AC low side up to 130 to 135psi. If that does not cure the problem, then an inductive ammeter should be used to check running amps on the compressor- it should not exceed around 7 or 8 amps on each leg.

  • Joe Pavlick
    Joe Pavlick
    Posted on 12/9/2020

    Recently installed mr cool mini-split. Customer called to report F5 code is showing. I will be going to check the unit. Since I do not have the manual in hand, what should I look for?

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 12/9/2020

    F5 error code indicates that the outdoor fan speed has been out of control.

  • Frank Cowles
    Frank Cowles
    Posted on 11/23/2020

    Have mod# A-18-HP-C-230B with 1 unit indoors . Have E3 code come up ,Indoor fan over speed , Shut down power ,pulled Batterys out of remote ,problem still there . Please advise . Thank you ,Frank

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 11/24/2020

    Give our tech support team a call at 270-575-9595 x300.

  • James
    James
    Posted on 9/30/2020

    I installed a 30k dual zone Mr.Cool mini split and it seems to be working at first when I call for cooling. The outdoor fan comes on the Indoor fan seems to be blowing decent. But after about 5-10 minutes it will flash a p6 code for a few then go away and a couple times the outdoor unit turns off and will eventually kick back on. I opened the king valves connected all the lines property before turning the system on. Any reason for this code?

  • Dan Danowski
    Dan Danowski from Ingrams
    Posted on 10/5/2020

    P6 code indicates there is a problem with refrigerant pressure. Please give our tech department a call at 270-575-9595 x300.

  • Faisal
    Faisal
    Posted on 9/14/2020

    Orient inverter p0 p4 p2 what is this

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

    I'm sorry, but that's not a brand I'm familiar with. I don't have any technical information on Orient units.

  • mike
    mike
    Posted on 8/26/2020

    I get no error code but the suction line ices up at times, the indoor fan speed seems low even tho it is set to high. Filters are clean and the outdoor unit never shuts off. Why is the pipe icing?

  • Kyle
    Kyle from Ingrams
    Posted on 8/27/2020

    It could be low on refrigerant. Give us a call at 270-575-9595 x300 to speak with our tech department.

  • christian
    christian
    Posted on 4/8/2020

    I encounter a P4 error on my carrier window type inverter ac. Is there a DIY means to fix it?

  • Kyle
    Kyle from Ingrams
    Posted on 4/8/2020

    I'm not sure what specific model that is. Give us a call at 270-575-9595 x300, and we will try to help you as best we can.

  • Austin coulter
    Austin coulter
    Posted on 3/31/2020

    I keep getting a p4 error code on my Michu-18avh2. An inverter compressor code. Everything is working fine but the compressor won’t turn on. How can I fix this problem?

  • Kyle
    Kyle from Ingrams
    Posted on 4/1/2020

    Austin, I'm not entirely sure what product that is, since I can't find anything with that MPN. Give us a call at 270-575-9595 and we'll do our best to help you get to the bottom of this.

  • Dennis wutzke
    Dennis wutzke
    Posted on 2/23/2020

    New unit 18000 btu 220 no heat p4 code

  • Kyle
    Kyle from Ingrams
    Posted on 2/24/2020

    Please call us at 270-575-9595 x300 for technical support.

  • Harvey Griffin
    Harvey Griffin
    Posted on 2/10/2020

    I have the diy Mrcool 36,000 heat pump now after about 4 months of using it when I change the temp up or down I get a code ( OF not fo ) don,t see any thing about this,the temp does change but why the code.

  • Kyle
    Kyle from Ingrams
    Posted on 2/11/2020

    In some modes (swing, turbo, etc) when those functions are turned OFF there will be a momentary “OF” show up. Try resetting the unit by turning off power and removing batteries from the remote, wait 5 minutes, then reinsert batteries and turn power supply back on.

  • John
    John
    Posted on 1/20/2020

    Good evening I installed my mr cool diy 24000 unit worked great for a week now getting a p4 error code

  • Kyle
    Kyle from Ingrams
    Posted on 1/21/2020

    Definitely give us a call at 270-575-9595 x300 for technical support.

  • Ron
    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

  • Zowie
    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.

  • Cory
    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.

  • Greg
    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.

  • 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.

  • Debbie
    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.

  • 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 :)

  • 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.


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