12 y/o multi-split issue

[Tanaka]

I have a multi-split (two head) system. Been working fine for 12 years.

One of the head units is not getting hot or cold. It starts up the compressor ok.

Am I right in thinking this can't be a loss of refrigerant (otherwise both units would fail)?

I'm an electrician, not an AC guy, so I am wondering if this is something I can fix before I call someone out.

[frank]

difficult to diagnose on a forum as we would need pressures and temperatures to point us in the right direction.

it may help if you posted make and model as some brands have inbuilt issues

[kiwifridgie]

Check the eev coil. Swap the two and see if that fixes the faulty unit.
More info can be provided if necessary.

[Tanaka]

Do these pictures help?

15555
15556
15557

[kiwifridgie]

Only manual I can find is an owner's one- tells me nothing.
The top pipe and 3rd pipe down are the liquid lines. Open cover and trace those pipes till they come to a valve with an electric coil on top, swap those coils over incl where they plug on the PCB.
Hopefully your unit will start working.

[Tanaka]

Thank you.

[Tanaka]

This thing? How do I take it off. I see a bolt on the front.

15558

EDIT: Actually, searching for that part, it's coming up as a 4 Way reversing valve. There are two of them. You can just see the other in the background, top right, the other way round.

[Tayters]

Looking at the data plate and the fact you say there are two reversing valves then I'd imagine there are two separate refrigeration circuits. If that's the case and guessing you can't check any pressures then get the faulty circuit only set to run and see if there's any power to the compressor or any pressure switches open circuit for starters.

Cheers,
Andy.

[Tanaka]

Yes, two compressors in there. It's dark now. I'll probe about with a meter tomorrow.
Thanks.

[kiwifridgie]

Thanks for your input Andy,
Sounds like someone is going to need some gauges.

[Tayters]

Cheers, they might well need them!

Not that I've ever seen one in the flesh but a previous job I had at a wholesaler, we had a few calls on similar Fujitsu systems.
These 2 compressor systems were still dogging on, half in some cases. Typically units with faulty compressors were the ones where you had to take the working one out to get the faulty one out.
Despite being two completely separate systems the common PCB wouldn't let you use one on heating whilst the other was coming. Shame, a heat recovery split would have been a first!

[Tanaka]

I fixed it.

Bad capacitor. There were two Toshiba compressors inside. The smaller one fired right up with a new cap.

[Brian_UK]

Glad you've sorted it and thanks for letting us know.