Daikin FTYS20BVMB green led blinking

[Aender84]

Hello all. I'm having a problem with my Air Cond. The indor unit is FTYS20BVMB and suddenly it stopped working. It was unplugged for a couple of minutes, maybe hours and after i plugged it back on it gave me this problem. I found out how to read the error codes and it gave me a long beep so i got the U4 error witch it seems to mean System Transmission between indoor units. I tried to switch the input power braker off and on again but the problem persists. Does any of u know witch may be the cause and what can i do to solve it?

Thanks a lot

[Brian_UK]

Have you tried switched the power to the outdoor unit ?

[Aender84]

welll yes... in fact the outdoor unit only has power cord. i see that there is a kind of box out of witch come out the refrigerant agent and also a power cable for the indoor unit... i'll try to unplug the cables from that too... But i think is the same as long as i closed the general braker

[brunstar]

if you have just unplugged the indoor unit this will be the communication error you have, you will have to turn the outdoor power off too.

[Aender84]

that's what i was trying to tell u... i only have one power cord cable witch i suppose it powers both indoor and outdoor unit

[Aender84]

one more detail... I opened the wire box of the outdoor unit and I've noticed that from the incoming wires, go out 4 wires 3 wires to power the indoor and outdoor unit and 1 for ground (2 black wires, 1 blue and 1 green-yellow). Besides that, when the power is on, the outdoor unit has a thing clicking inside it, and I've noticed that is right next to the wire board.

[airefresco]

The 4 wires are 3 for the power to the indoor unit (live, neutral and earth). The fourth cable is the communications cable between the indoor unit and outdoor unit. The U4 fault is caused by a communication error between indoor and outdoor unit, which could be caused by a few things.

First thing to try is turn the power off to the unit for a few minutes, then try again. If that doesn´t work then check the communication cable at both ends. If that doesn´t work, it´s likely to be something more serious.

The clicking sound is probably nothing to worry about, they do this when you first power them up.

[Aender84]

with the wires i got it. As for the communication cable... is it the same with the power cable? or it's something else? For the ticking part... it seem to tick for more than 10 hours. I try the thing with turning the power off first time. In fact that's how i realized it doesn't work anymore; it was unplugged because i needed the plug for something else.

[airefresco]

Swap the live and neutral around and try that. I´ve no idea why that makes a difference, but I once had a unit which was showing a U4 fault and switching the live and neutral worked. If you have the same style European plugs that we have, then put the plug in the other way, it´s the same as switching live and neutral.

As for the communication cable... is it the same with the power cable
Yes. Inside the terminal cover of the outdoor unit, you have 4 terminals, 1=Live, 2=Neutral, 3=Comms, 4=Earth. They should go to the indoor unit.

The clicking noise doesn´t sound good. Normally they do that for a few seconds at start-up, not constantly.

[Aender84]

thanks for your hard work on helping me. Tried the reverse live with neutral also (i reversed the plug) and it's the same. As for the communication cable it's ok. it worked before and had no intervention on it. As for the clicking thing... it's still there and it keeps going although the unit is not functioning (it's being switched off from the remote)

[airefresco]

There are 5 possible causes of U4

- Faulty indoor PCB
- Faulty outdoor PCB
- Indoor unit-outdoor unit signal transmission error due to wiring error.
- Indoor unit-outdoor unit signal transmission error due to disturbed power supply waveform.
- Indoor unit-outdoor unit signal transmission error due to breaking of wire in the connection
wires between the indoor and outdoor units (wire No. 2).

Unless you have the tools, you are not going to be able to test those things sufficiently.

There is a few things you can do. Firstly, is the LED at the outdoor unit flashing? It´s located on the left of the power terminals and marked as LED-A.

Double check all wiring connections (including the plug) at the indoor and outdoor unit to make sure they are good connections.

If you are able to, check the voltages at the indoor unit between 1-2 and 2-3.

If that´s all good then it looks like you will have to call a profession in to look at the system.