This post may not be of interest to most my followers, but I hope it will be helpful to other Mitsubishi mini-split owners who use the Kumo Cloud App with WiFi to control their heat pumps.
Yesterday all six of my heat pumps began disconnecting from my WiFi and I have not been able to communicate with them until about 9:30 AM this morning. The details are strange and suggest to me that Mitsubishi has pushed some firmware update to these six devices that prevented them from connecting to my WiFi until mid-morning. As of this moment they seem to have restored their network connection — but there is no communication from Mitsubishi that explains what is going on.
What follows are more details of my experience. If you don’t own Mitsubishi mini-splits or use Kumo Cloud you probably won’t be interested in reading on.
I have six Mitsubishi mini-split heat pumps that are all connected to my network with WiFi adaptors that communicate using the Kumo Cloud App. Apparently Mitsubishi is in the process of rolling out a new app to replace Kumo Cloud. They call it Comfort by Mitsubishi Electric. If you go to the Apple App store and try to download Kumo Cloud you will get this new app, instead.
I have updated to the new app on my ipad, but on my iphone I did not update so that I still have the original Kumo Cloud App.
My Home Assistant program actually uses a Kumo Cloud integration to control/monitor my heat pumps over my local area network — uses the ip addresses and Kumo protocol to communicate with them without going out to the cloud. So even when my ISP is down and I have no internet connection, Home Assistant is still able to communicate with my six heat pumps — though the cloud apps on my ipad and phone do not have communication.
Yesterday Home Assistant lost its connection to all six of my heat pumps. I re-loaded HA, I rebooted HA, I updated HA, I rebooted the heat pumps — nothing fixed my connection. My Kumo Cloud app suggested all HP were off-line. I updated the App on my ipad to the new Comfort App, and after some time (a few minutes) it reported the HP as being disconnected from the network.
All six heat pumps have been assigned static ip addresses. I tried pinging them and they would not respond. Other devices on my network continued to work properly.
I rebooted my Deco X-20 access points. I rebooted my pfSense router. Nothing I did could get these six heat pumps to connect to my network. I spent about 3 hours this morning messing with all this.
Then, about 9:30 AM, the heat pumps began to connect to my new Comfort App. Several of them could be controlled with the new App. Others showed up, but the App said they were “off.” I see no way in the App to turn them “on.” I don’t know what off means — but the app is giving me no control of them.
I found that I could ping all six of the heat pumps again. I re-loaded my HA Kumo Cloud integration and all six heat pumps re-connected to HA. I can control them and read their parameters and HA seems to be re-connected as it should be.
But the Comfort App still shows two of the heat pumps as “off”.
And, I am not home free yet. The heat pumps are still disconnecting and re-connecting to my network. Mostly they are connected, but every now and again when I check, one or more is disconnected.
I don’t know what is going on, but this roll-out by Mitsubishi is a disaster. Their Comfort App sucks. Whatever changes they have made to their WiFi boards has bugs — and there seems to be no information provided to consumers to explain what is going on.
Coincidently, my heat pump installer (Dave’s Appliance) had a crew next door working on my neighbor’s heat pump. I stopped over and asked the service tech if he could explain what was going on with the WiFi communication. He said they are getting lots of complaints from customers but no explanation from Mitsubishi. Mitsubishi tells them that there will be erratic behavior for the next couple of months.
This is simply unacceptable.
The Pragmatic Steward 
Same experience in CO. I also had my unit that was still online reporting an incorrect temperature (63 when it was 67) – while the unit knew and turned itself off with the appropriate temp (67) set in the new app.
Advanced notice of updates and messages that “we know there are problems, stand by” would save us worry and hours. (Thankfully, we are 2h behind you – so I wasted less time.) Agree w your assessment of this new (cr)app.
P.S. This is the 2nd time I sent their techs a problem query, and I suspect the 2nd time they rebooted my individual account. Both times it seemed to fix the problems. Rec. sending problem tickets to their techs before spending time….
The same in AZ. Mine was working fine until a couple weeks ago when it disconnected from my WiFi and wouldn’t reconnect. I made the mistake of removing the device and zone. When trying to re-add, it all works fine up until it tries to “check for firmware”, and times out, failing to even add the device or zone. The “contact support” in-app feature results in an immediate, “There is a known issue, and we are actively working to resolve it as quickly as possible.” Yet periodic requests for an update are unanswered.
Mitsubishi has substantially changed the API to the Kumo units and seem to maintain support to older units through some type of “Legacy” support. Mitsubishi’s new Comfort app seems to use a new server protocol; quietly, Mitsubishi has started save authorized a complete changeout of older Kumo units to their newest version, model number ending in WF-2
https://www.mitsubishicomfort.com/wireless-adapter-upgrade
I had all the issues that most report here after “upgrading” to the Comfort app whilst using my existing, fully installed and previously functional system, using WG-1 Kumo adapters. It was a disaster; once a WF-1-controlled zone is removed it is impossible to re-register the Kumo unit back to the cloud using the new Comfort app. Don’t delete a zone!
I called my HVAC company and they well knew about Mitsubishi’s Kumo upgrade program (and are not happy about it, Mitsu is not being fully communicative with them, is making them go through procedures which complicate the service, and worse are currently making *customers* pay for the servicing necessary for the upgrade with a promise to reimburse the customer later).
Anyway, I removed all the Kumo transmitters from the units myself, went to the contractor’s office personally to switch out the units to WF-2’s rather than wait for a service that fit into their now hectic (thanks to all this) schedule, and installed them myself. NOTE: Mitsubishi changed the CN-103 interface cable so you MUST disassemble each interior unit to get to the electronics board in order to completely switch out the cable – it is not a simple plug-and-play swap just because you accessed the Kumo unit alone. I installed all 4 WF-2 Kumo units, about 2.5 hours. Everything works perfectly! The Comfort app now is reliable and highly reactive to settings updates.
My experience was not nearly so painful — but I am waiting for the second shoe to drop. After a few days of chaos I was able to get the new Comfort App to work and my Home Assistant Kumo Cloud integration started working again. But it appears that the demise of this integration is just around the corner and I will be SOL.
I didn’t have much of a choice in getting my Kumo system to work reliably, as I have a ceiling cassette and, thanks to the previous WF-1 Kumo’s design, I could only have 1 controller, that being the Kumo. No Kumo, no ceiling cassette control *at all*.
The new WF-2 Kumo unit has a pass-through CN-105 connector and for the first time enables you to use 2 controllers; I have a MHK2 wall thermostat ordered as we speak. Finally looking forward to having a wall controller!
I have the PAC-USWHS002-WF-1 unit and I’m still not able to get beyond “Check for firmware update (Legacy)”
So frustrating. I can’t even get them to respond through the App help.
You won’t. Same thing happened to me after I deleted a zone and tried to reconnect: failed at firmware update. It will never pass that point, I tried everything including attempting to use the Kumo Legacy app and using different phones.
You will need to contact Mitsu or your local Mitsu HVAC contractor to arrange the warranty swap to the new WF-2 Kumo modules.
UPDATE: After a month of waiting, and a poignant message stating that their upgrade had essentially removed a key, paid, feature and how it is frustrating and disappointing that Mitsu has neither addressed the problem nor showed any willingness to take action, they finally reached out last week to explain that they are still working the problem, but wanted to ship me a replacement adapter!
I am happy to report that self-installation went well and I am now back up and running on a new WF-2 unit. Sometimes it does pay to be patient, yet relentless.
I have spent far too many hours on this!
Beginning on June 25, my app no longer connected to the wireless interfaces on my four indoor units. Doing some online research, I figured out how to access the interfaces, reset them and set them to pair. I attempt to reconnect via the app, it recognizes the interface, shows the correct 6 characters from the mac on the interface, runs through several steps until it gets to “firmware update”, where it spins for 10-15 minutes before ending with the error “unit failed to connect”.
The app is finding my interface units on the network, displaying the 6 character codes, but it is never able to complete the connection.
I have been on the phone troubleshooting this with Mitsubishi for HOURS. I have reconfigured my network, turned off everything but the 2.4 connections, restarted everything multiple times. I have even gone as far as connecting a dedicated 2.4 router…
Per my last conversation, they have exhausted all phone troubleshooting, and suggested that my interface units all stopped working on the same day… I have a call in to the contractor that did our install, and they’re going to come out and potentially replace all four (covered under warranty, but I will still need to pay for service call.
And here we are, months later, the zones go offline randomly, home assistant integration is bust because I had to reset and setup everything again through the comfort app, so the kumo integration doesn’t connect to my account. So disappointed. Every IoT provider out there sells features like Google or Apple integration. Mitsubishi, no…. They want to keep it all in house and then can’t even get their own services working well. I have cheap Chinese devices that work and integrate flawlessly for years.
If you have not bought a Mitsubishi heat pump yet….dont.
Yesterday three of my five heat pumps began disconnecting from my WiFi . About 1 week ago I updated to 3.2.2 comfort app. The older comfort app has been working fine since mid Aug. 2025, and since the update I loose connection and the comfort app only sometime lets me change my heating temp. ? still Neds more work.
sorry for slow response.
I am trying to avoid any updates since at the present, my six heat pumps are all communicating well with Home Assistant. I have heard other folks are having lots of trouble with Home Assistant since the Comfort App came out.