Daikin indoor unit totally dead :(

[craigix]

Hello everyone, first time poster, long time reader.

Right, I've installed aircon/heat exchanger units before, some background is we live on the edge of the Pennines and don't have gas so use these to heat the house, we have one for each room.

Just installed a Daikin RYN35CVMB (indoor FTYN35CVMB) in the bedroom and it was working fine for a couple of days, went to turn it on yesterday and the indoor unit is dead. No light, nothing. Was working fine a few hours before.

Outdoor unit still has power but does nothing, changed power wire, checked connections at all ends. Changed plug fuse.

The unit was secondhand but I bought it working from an installer, it was working after I installed it. Now it just seems to be dead.

Is there a fuse on the indoor unit? What would cause even the light not to come on?

Googled all over, found many service manuals but they all rely on that light or the remote, or the outdoor unit having LEDs.

Is there a fuse in the outdoor unit?

Got a cold and angry other half and it gets COLD here in winter, I'd much appreciate any advice as it's very hard to get engineers to come out here, last time it cost £150 just for him coming out, and he didn't want to do it.

[airefresco]

First check is if there is power to the indoor unit by testing across the 1 and 2 terminals. If there is power there then it is something on the indoor unit. If there is not any power there, then check the same terminals at the outdoor unit. If you have power there, then it is something on the cable between indoor and outdoor unit. Still no power there then it´s something on the outdoor unit.

On the indoor unit there is 3.15A fuse, pretty much the centre of the PCB. On the outdoor unit there are 2 fuses, but I think you will find it´s not going to be either of these. More likely the indoor board/fuse or a something on the cable.

Be careful because if you frig the board it´s going to cost you much more than 150 quid to get it fixed.

[craigix]

There does seem to be power to the indoor unit, but it's just not coming on.

How will I go about safely taking this unit down (I'm worried about the gas), or can I get to the PCB while it's on the wall?

I've seen an unused indoor unit, this exact model, for £25 not too far from here (some old unwanted unit, assume conservatory), so I'm considering just doing a straight swap. I'm guessing that's a lot easier than going down the repair route?

[airefresco]

No not necessarily. If you´ve got power to the indoor unit, then it´s probably just the fuse or possibly the board. The PCB is behind the terminals you checked for power.

Turn the power off. Check at indoor unit to make sure power is off. Take the cover off the the unit. Take the terminal block off and disconnect everything you can (remember where all the plugs go). The PCB is in the black box on the right. You´ll mess around for ages trying to get it out, but once it´s out you´ll be able to see the fuse.

IF the fuse is OK, leave the PCB out, buy that other unit (assuming it´s the same model you have) and put the PCB from it in your unit. That´s much easier then taking the unit down and messing around with gas, etc.

[craigix]

Thanks for that, I got the board out, fuse ok, changed the earth (seemed slightly corroded) but still no joy.

It does just seemed to have lived that short time and died.

Any idea how expensive a brand new board might be? I'm a little wary of getting another second hand unit, unless a new board is a crazy price!

[airefresco]

No idea our prices here are different, I would imagine that it won´t be cheap though.

Just a thought, but are you sure the remote is OK?

[craigix]

Well the remote was working, and it boots up ok, I've tried a reset too. I thought using the on/off button on the actual unit would override the remote anyway.

The last time I turned it off I did use the remote, but surely the unit would not just play dead until the remote was using again? Or would it?

I'm looking at just sending the PCB off for repair now.

[Yuri B.]

Hello!
If you

live on the edge of the Pennines

(sorry, dont know however where it is) it may also be useful to look at the power supply quality so that the new/repaired PCB would not follow the route of its predecessor.

[Yuri B.]

It does just seemed to have lived that short time and died.

I also, just in case, would test the compressor - with multimeter and then turn it on for few seconds, measuring current.