Hey all,

Firstly, I've already written the installers. But seeing it's a weekend, I'm unlikely to get anything back until Monday I recon.

Anyways, in short, today, my (relatively) newly installed Daikin HVAC faulted out, with all internal units spewing a U0 - 00 error. I had a google and it looks like the error is refrigerant related. Which makes me worry if its leaking?

I don't know much about HVAC systems, but how risky is it if this is leaking? its R32 gas in there, is it safe to stay in the property for family (and pets) if there is a possible leak on the system?

I have a Daikin 24k that has been a major pain and at this point throwing money after money at the problem.

Started with a water leak at the head unit, which has happened before usually in spring after switching it from heating to cooling. After cleaning out the unit we turned it back on and started giving us a U0 error code. Had my tech come out and it had some weird pressure issues which was thought to be to low refrigerant. So he topped off the refrigerant still showing U0. We replaced the linesets and recharged the lines. Still showing U0. Last two things to try on the U0 code sheet was PCB board and expansion valve. We decided since it was middle of winter at this point and the/cost to replace those we decided to buy a new condenser and fix the other one at a later date. So still nothing and still showing U0. My tech spoke with the daikin techs which basically said to try and replacing the head units PCB. For $200 I thought it was worth a try. Replaced it and as soon as it was hooked up and power turned on we finally got heat. But that lasted for maybe 3-5 days and then back to U0. So now what….daikin said to replace the thermostat board (the little white bulb on the front of the head), so that’s another $100+ to maybe see if that works. Also want to mention I tested the voltage at the disconnect box and showing 240v on incoming power and outgoing.

I’m so close to replacing the whole head at this point and for how much I’ve invested in this fix. If anyone had a suggestion please let me know.

We had 3 mini splits installed in our home 5 years ago. After about 2 years, they started showing error code U0, repair person came, found a leak and fixed it.
Now, 2 years later, the 3 units keep shutting off every couple of hours and showing U0 code again. If we flip the breaker, they will work for a few hours then shut off again.
Another maintenance person came last week and said the pressure looked good and it's blowing cold so he didn't expect there was a leak. After a bunch of wandering around and not really taking anything apart, he concluded that there was reduced airflow because there was some dust inside the unit (not the filters that you can take out--those were clean). He said we would need to pay for a maintenance package if we wanted someone to come clean out the units to resolve the problem even though they are under warranty until 2030.
Any ideas what else it could be as I've read that this code could be caused by a faulty valve, compressor etc too.

I'm new homeowner with a minisplit system. I've got 4 indoor units. One of my indoor units (CTXS09HVJU) is showing U0 error code.

According to the spec sheet, that's either a low refrigerant issue, or an issue with expansion valve.

I had a tech out and he believes it's likely a leak. He wanted to diagnose the issue by first:

1. Weigh the charge and see if it matches manufacturer specs. If it matches, we can conclude there isn't a leak.

2. If it doesn't match, he wants to cut into lines, sectioned off to each indoor unit, and pressurize with nitrogen. Then would leave overnight to see if the pressure remains constant.

Step 2 makes sense to me, but it seems invasive, and maybe premature? Are there other steps that should be considered first? I would think a faulty expansion valve would be less invasive to check.

Also only one of the indoor units has the U0 error code, shouldn't the leak be there? It appears to be 4 separate refrigerant lines. Or do all the lines connect together in the outdoor unit? The indoor unit with the error code is furthest away from the outdoor unit. So if the lines are all connected, it makes sense that this would be the first to have the error and eventually all the units would have the error. However, we've only been running 2 of the indoor units (indoor 3 and indoor 1). So I don't think refrigerant should have even been flowing to the other 2 units, so the leak shouldn't be there, right?

Regardless it seems excessive to cut into lines and cap off 4 separate sections for each indoor unit for pressure testing, at least for a second step. I've included a basic diagram of the system. We've only been running indoor unit 1 and 3. Indoor unit 3 is the one with the error.

Any advice would be appreciated. Just looking for a second opinion. They will charge by the hour for this work.