Five Head Daikin Mini-Split Troubleshooting PCB Board Non Functional. EP35

[@jericosha2842]

Thanks for being wiling to share. I often feel lost in space with these units.

[@sergioramirez9025]

HEY BRO THANK YOU SO MUCH!!!! IGNORE ALL HATERS... ITS TECHS LIKE YOU THAT MAKE THE NEW GENERATION TECHS BETTER... KEEP POSTING THESE BEAUTIFUL KNOWLEDGE VIDS FOR HVAC TECHS. I APRECIATE YOU ALL THE WAY

[@ericafors6039]

Wow! Finally someone who knows what the heck they are doing troubleshooting a Daikin minisplit. We have techs come out and they are clueless, especially when it comes to the control board components. Thanks so much! 🙏

[@USA-GreedyMenOfNoIntegrity]

That’s because most of us are not trained to diagnose and troubleshoot PCB’s and communications errors on this new equipment. We’ll get there, but it takes time. Just like CEOs in the USA, it’s taken time to outsource all of our manufacturing jobs. I bet when you started your job, you didn’t know everything either.

[@hotrod7696]

In practice first I check for shorts on the zones to avoid damaging a new board. Good video, thanks.

[@crowderglen]

Good fault finding! Just remember that the fuse’s job is to protect the cable. Bypassing fuses for fault finding is okish but leaving the bypass in permanently means that these cables were not protected. Any way, great job getting the system going!

[@asherroberts2065]

You are fantastic tech man thank you for owning your mistake and then showing the rest of us. Your ability to learn after a mis step, and then a quick bounce back with a quick reevaluation providing a proper repair revelation. You suffered for the rest of us for that I salute you🫳

[@vrmntthb]

Great to have a back story to when it went bad and how many hands were around in equipment before you got there…. Thanks for your insight…

[@colinandpattyhowie2887]

Thank you for being so honest and candid I know when I'm working on certain things that get worse before it gets better sometimes and although I wish it wouldn't happen that way we seem to learn from the process of trying to troubleshoot things and realizing a better way to do it after we try something at first.

[@heattransfer9476]

Man those hard days will never be forgotten thanks for ur knowledge

[@NighthawkHVAC]

Thanks for watching. Glad I could help.

[@jashua2089]

We all make mistakes, keep posting such great videos, i really like them.

[@dnnsmrgn]

Was a great video, the only thing I would have done different was desolder fuse and solder in another one .

[@LC-qi5ff]

Thank you so much, this was really helpful

[@hrdworkin7633]

Great Video...the new Mini Splits are a challenge. Just a thought...maybe use a fused bridge next time to protect the remainder of the components. Thanks

[@HVAC69]

Great Video your a Pro-Expert !!

[@robbyjones8321]

You would think that crazy massive board would have high voltage protection for something like that, it’s not your fault, how would you have known to test for that, the warranty tech support guy should have said to test that the first time you called them when they thought the board was bad. You did a Good job 👍🏻

[@Gatsu1995]

It has a fuse for the high voltage.

[@Darny1able]

daikin had issues with those boards would fail after about 11/2 years . the capacitors become weak i replaced quite a few under warranty

[@GothamGreenSauce]

Great job brother

[@emilionunez4566]

That was some good training for me 😂 thx

[@dell177]

We all learn from the mistakes we make, it's just a price we pay. Daiken dropped the ball, they should have protected the board against an external short. I designed power supplies for decades and we always designed over current protection into them so it would shut down if to much current was drawn. Fuses are supposed to protect you from an internal power supply fault, they should not be used to protect against an external fault.

[@OthmanAlikhan]

Thanks for the video =)

[@fisqual]

I'm sorry to be 'that guy' in the comments but... I would think if you can go to fry's for thermal paste they probably sell that fuse there as well. It's inconvenient that it's a solder-in fuse, but should be really fast & easy to replace if you've ever used a soldering gun.

[@noside8469]

Its fine bro. Shit happens sometimes in our line of work... though we learn it the expensive way 😊👍❤👏🇵🇭👊

[@loromachaco1]

yup happened to me as well, mine blew up though...

[@taba9221]

Thanks for sharing

[@tungtung4229]

The 5 ac supply cables to the 5 indoor units seem to be connected in parallel at the connector terminals A, B, C, D and E then connected to the PCB via a white and a black wires (smaller size compared to the main supply black and white wires from the main terminals to the PCB). This setup can be seen clearly at 11':28 - 11':30 . Just wondering whether the circuit breaker at the Main Switch Board tripped at all or only the small fuse on the PCB?

[@NighthawkHVAC]

Only the fuse blew.

[@nickknickle7878]

Great video, thank you

[@TopLineHeatingCooling]

Thank you for that tip. Wow!

[@andresperez-wc8ty]

Oh man what a bummer. Cant win em all !

[@JacobGloria-g3b]

I have power to all heads. But getting a UH code, which I believe is a communication error. When I check DC volts between 2 and 3 I am getting 0?

[@NighthawkHVAC]

You should be getting fluctuating DC voltage. If not that means it’s not communicating. Try removing the wires and reset. If the voltage is there then you have either a wiring issue or a bad indoor PCB. If you can’t detect any DCV then possibly a bad outdoor board. I’d suggest checking the service Manual for more details. www.daikinac.com/content/assets/DOC/ServiceManuals/2017/MXS-Service-Manual.pdf

[@hectormercado8065]

Why don’t you wire a surge protector in series with the disconnect? May save the customer another board lol

[@Killer96z]

May I ask why didn’t you just replace the fuse?

[@NighthawkHVAC]

Brand new install. And under warranty.

[@CHIBA280CRV]

Cool 👍🏼 but why didn’t you just solder in a new fuse instead of purchasing a new board ? Did you have to purchase the new one from your pocket ? Or did you say it was defective and got a new one ? I wonder if the horrible tech will answer 😂👍🏼👍🏼👍🏼👍🏼👍🏼

[@NighthawkHVAC]

It was under warranty. If I soldered a new fuse that would also void the warranty.

[@jerryfaircloth]

I would have just soldered a pigtail fuse holder to the blown fuse location so that you wont need to replace the whole board each time. That's a very poor design by daiken. I have one of these I am trying to troubleshoot for a friend but its fuses test good but still no lights come on the head unit. Bout to pull out some hair. :)

[@grapeshot3462]

Aren't you supposed to wait at least 5 minutes after disconnecting power before messing with the board? I thought those capacitors on the board can hold a charge for several minutes.

[@michaelcostello6991]

So what if they hold charge when you are not touching them or any other conductor ?

[@ericafors6039]

The service manual for my RXS24LVJU advises waiting 10 minutes.

[@bobgallo2178]

Wait ten minutes, d c power will grab you and ya can't let go. That was told to me at a training session. I'll take their word for it.

[@HVASEA]

Leave the bad fuse in...Solder in two female spade terminals and use an auto fuse...(if it's out of warranty)

[@GurmeetSingh-rk6us]

My diakin AC is cooling but it doesn't stop inbetween. It keeps on running and keeps on cooling. We turn the ac off to stop if from cooling too much.. where can be the problem?

[@NighthawkHVAC]

Could be the indoor thermistor is bad and is not detecting the temperature properly.

[@johnedwards4012]

What up Wes!

[@bigdaddy4975]

I wouldn’t swap that board nothing is wrong with it. That’s why it has a fuse to protect itself

[@mikemarksmusic]

good video. Just curios Have a daikin 4msx32gv-ju all works fine but one head unit of 4 .The head the has green flashing shuts off in heat or ac mode or auto. Vents close and wont power up Outside unit. It will work at times and intermit problem I got a J3 J6 double beep code in diagnostics . Not sure if it is the pipe thermistor indoor or out door or pcb board on ot door or indoor unti. Had tech here and i knew more than him so called Daikin they wont talk to me without Hvac certification. Any ideas would be appreciated. Unit is 12 years old and in excellent shape. Works fine with all other 3 heads .

[@NighthawkHVAC]

J3=Malfunction of discharge pipe thermistor Defective connection of thermistor Defective discharge pipe thermistor Defective outdoor unit PCB J6=Malfunction of heat exchanger thermistor Defective connection of thermistor Defective heat exchanger thermistor Defective outdoor unit PCB I’d start by checking all the connection points then test the thermistors.

[@mikemarksmusic]

@@NighthawkHVAC thanks for reply. Wish there was a, video on the outdoor thermistor for Daikin. Three service techs came here not one had a, clue. Schmaditcs are horrible from Daikin.

[@danduvall2658]

Pcb board and thermistor faults are the most common problem I run in to out in the field. Seeing how thermistors can be replaced relatively easy and cheap I usually start there. Tech support would have you ohm out each thermistor but the leads are so tiny its pretty difficult and I believe quicker to just swap them out. It is almost always a faulty thermistor at the discharge line of the condensing unit but of course be sure to check pressures before replacing anything. If the unit is low on Refrigerant or overcharged it can also trigger a thermistor fault (if a pressure fault hasnt displayed first).

[@erixgar4117]

hey man how did you do ? did you pay out u pocket for the second PCB?

[@NighthawkHVAC]

Nope. Was covered under warranty.

[@ThatEMOguy74]

I need all the thermal paste you have in stock!

[@NighthawkHVAC]

Me too!!!

[@w0lvez1]

Why everything on the board of Daikin is made of Panasonic? Do Panasonic also owns Daikin?

[@oliverlewis6277]

Why not just replace the fuse? Why do you need to replace the board?

[@NighthawkHVAC]

Brand new install. If he has issues down the line doing a field solder would void the warranty.

[@ktk575]

solder on a new fuse and good to go haha

[@HVACGUY]

Great video! Was the fuse not replaceable?

[@NighthawkHVAC]

It was soldered on and under warranty so I just replaced the whole board.

[@mihaiachim5299]

⁠​⁠​⁠​⁠​⁠​⁠​⁠​⁠​⁠@@NighthawkHVAC why offer a warranty on something destroyed by external causes? If I were a manufacturer, I would refuse to offer a warranty on such defects... I would risk losing sales because the people on the ground would no longer recommend my products to customers because the manufacturer does not want to repair under warranty products damaged for example by technicians :))

[@jamessmearer117]

Hi there. Great video! I have a question for you. I own a Diakin mini split model: RX18NMVJU (outdoor heat pump) and last night during a snow storm the unit stopped working. Today I took a look at the heat pump and noticed snow on the electrical contacts and a little snow on the electrical board. I was wondering if the board is fried or would the fuse be blown? I have a U4 code. Your help is very much appreciated l!

[@NighthawkHVAC]

The code U4:Malfunction of transmission between indoor and outdoor unit Short circuit in indoor-outdoor or outdoor-outdoor transmission wiring (F1 / F2), or wrong wiring Outdoor unit power supply is OFF System address does not match Defective indoor unit PCB Defective outdoor unit PCB I’d suggest turning off the power and removing the snow. Make sure your system is fully dry. Then restore power. If it still doesn’t work you may have an issue with the board. At that point I’d suggest contacting your local licensed HVAC company. Good luck!

[@tjrogers4079]

Nice 👍🏻

[@Patech87]

Question why replace the board if it was just the fuse why not get a new fuse and done please help me understand thanx for your video helps a lot 👍

[@NighthawkHVAC]

The fuse on the control board is soldered on. If I found the right fuse and soldered it on it would void the warranty. Also this unit was new and still under warranty. Thanks for watching!!!

[@Patech87]

Thank you very much

[@bobgallo2178]

@@NighthawkHVAC Also, by soldering in a new fuse, you would be liable if anything else happens. Best just to get the board and let the manufacturer worry about it.

[@syedbasheer8210]

Thanks...👍

[@dariomendivelso3413]

Great

[@richardbartlett6932]

Wiring a condensate L+N on 1&2 will not cause a short or blow a fuse unless there is an issue with the wiring or pump ..

[@christopherrodenhiser8821]

Good video - I have the 4mxl and drain pain heater -u should show correct set up to wire that as I checked mine as power bill was way high - tech did not wire it to dp1 and dp2 on board but right to power where comes into from supply - in other words the drain pan heater on all time - even when machine off - why would tech not wire to mainboard to use the energy efficiency if drain pan heater only coming on when 0 and when in defrost mode instead of wiring it direct and it being on 24 hours a day 365 days a year - just wanted to make sure their a reason why they would not use the correct ports on the motherboard -dp1 and dp2 - I look forward to a response or post as this is also new system less then 1 yr old

[@315Habib]

Didn't you even check the fuse before you got the new PCB? How about the Daikin tech? Didn't they ask you to check the fuse?

[@NighthawkHVAC]

No I didn’t. Didn’t notice it till I blew the 2nd board. Tech support didn’t mention it either. I guarantee it will be the first thing I check next time.

[@315Habib]

@@NighthawkHVAC tough lesson, respect

[@dennisgriffin4048]

When you bypassed the fuse the unit worked fine. Why on earth wouldn’t they design it so that you could replace the fuse instead of the whole board. It seems like a waste to have to replace 2 boards instead of a fuse and if it wasn’t covered under warranty much more expensive for the owner.

[@NighthawkHVAC]

Agreed!

[@VietTran-vf7sc]

Did that mean the board was still good, just the fuse was blown, didn't it?

[@NighthawkHVAC]

Pretty much.

[@CR-hj1fs]

Hey Nighthawk I feel your pain. I have the same inverter and want to one of those boards? Let me know if your going to get rid of them. Thanks

[@NighthawkHVAC]

They were turned in for warranty. Sorry buddy.

[@CR-hj1fs]

@@NighthawkHVAC As it turns out, I measured each side of that fuse and it had 120v. so I thought it was good. After I removed the PCB and did a continuity check, then did it register bad. So some how 120v was back feeding to the other side without amps... I soldered in spade connectors to the existing fuse barrels and stuck a fuse in. Working great now. Thanks so much for the video it will definitely save some people headache.

[@sprockkets]

@@CR-hj1fs If a fuse is working you won't show any voltage when live. If it is open then you will see voltage.

[@alsur272]

Thank you for video. Seems like it been long day for you.

[@NighthawkHVAC]

A very long day indeed. Thanks for watching!

[@camtran4765]

Why not just replace the fuse?

[@NighthawkHVAC]

Voids the warranty.

[@johnmiller102]

Could have just changed the fuse instead the whole board?

[@NighthawkHVAC]

I could have. But it was soldered into the board and it was under warranty. Safer to just change the whole board.

[@jameshengston6029]

Nighthawk HVAC hooking up condensate pumps wrong and blowing out two circuit boards is covered under warranty?

[@NighthawkHVAC]

They took them as warranty to my surprise.

[@donnierobertson3088]

Ok

[@jon3862]

💪👌🤝👍👍👍