Toshiba multi split runs non-stop

[expat]

Hello everyone. I've got a problem with a multi split I installed in July.

UE: RAS-M18GAV-E
IU: 2X RAS-M10SKV-E

The call came last Friday that one of the units just kept blasting out heat non stop.

The other unit cycled properly whether it was working on it's own or in conjunction with the faulty unit.

As the faulty unit's connections went straight out the wall behind it I decided to make sure it wasn't just drawing air from outside over a temp probe.

After plugging the hole with silicon I switched the unit back on and after a few minutes I increased the temperature demanded. Off it went ,working away nicely and after a few minutes I reduced the temp setting to 21°C and as would be expected It slowed right up.

This morning the costumer called to say he had switched it to auto mode and the unit went into cooling and once again didn't stop even when the room got cold. He had not changed the temp setting.

I'm wondering if the problem is a faulty return air temp probe.

Could that cause this sort of problem?

BTW only the green operation light is on and not flashing. And I remember seeing the orange pre def on the other day but once again not flashing.

Has anyone else experienced this sort of problem?

Thanks for any replies.

[nike123]

I'm wondering if the problem is a faulty return air temp probe.

Could that cause this sort of problem?

Could be. Check probe resistance with R/T chart for that probe.

[paul_h]

Could be out of spec. As you say, no faults, so it's not short circuit or open circuit.
Can you compare the two units resistances, or better yet live voltages.
R/T charts may help in seeing if there's a bad fault but voltage is better. (you can tell if the PCB is putting out the right voltage too)
If you can't get data on voltages, or reach the probe pins with the unit running, it may be worth while swapping sensors or indoor PCBs.
If the fault still occurs in the same indoor unit, it may be a tx or outdoor PCB fault.

[expat]

Thanks for your feed back guys. I went back today and checked the probes against R/T charts. All was looking good.

So I swapped the card and probe sets from the two units (leaving the remotes and remote receivers as they were). Both units now seem to be running properly, but that seems odd to me.

I noticed the orange PRE DEF light coming on every so often (not flashing) but only on one IU at a time. During this time the unit in question would shut down until the LED had gone off, and then would resume normal operation. I would have thought the orange led would have lit up on both IUs at the same time, indicating defrost on EU.

PS I can't believe how inexistent Toshiba's after sales service is over here. Absolutely no way to get any help. It's a disgrace!

[nike123]

Sometimes, when you have odd errors, it is good to make "reboot" of system. That is achieved by completely disconnecting all power supply to outdoor and indoor units for more than 5 min.
After that has been done, many of odd errors can disappear!
When you swapped PCB-s you are also done that "reboot" and that could explain your case.