Indoor unit with faulty thermostat

[bittylicious]

Am I right in thinking that Faikin generally sets the target temperature to the minimum allowed (e.g. 18°C) when cooling, and turns off the cooling/sets the target temperature to something approximating the "Home" temperature when it gets close?

The reason I ask is that the internal temperature sensor in my unit, which I think is what Faikin reads as "Home," gives erroneous readings, probably because the unit is situated in a place with little room above and below. For instance, right now, my external thermostat reads around 26°C but "Home" reads around 19°C so I don't think it's trying hard to cool.

If my theory is right, is there any suitable workaround, e.g. for Faiking to say "Just cool it, dammit, and ignore what you think the temperature is," or to do something with the temperature sensor on the Daikin motherboard itself?

[sm-Fifteen]

If my theory is right, is there any suitable workaround, e.g. for Faiking to say "Just cool it, dammit, and ignore what you think the temperature is," or to do something with the temperature sensor on the Daikin motherboard itself?

Not really, no. That would be Powerful mode, but what it mainly does is set the target temperature to its maximum (30 or 18, depending on heating vs cooling), but if the temperature sensor is already reporting low temperatures, that won't do.

The reason I ask is that the internal temperature sensor in my unit, which I think is what Faikin reads as "Home," gives erroneous readings, probably because the unit is situated in a place with little room above and below.

If you set it to fan only mode, does the temperature actually settle to the actual room air temperature, or is the thermistor broken? If the sensor is reporting low temperatures like that because the unit is just that starved of warm air to cool, I don't think setting it to some hypothetical "walk-in freezer" mode would help. You could try setting a fan to blow hot air on it from above (where the air intake is), see if that does anything?

[revk]

The Faikin sets to home plus a lot or home minus a lot to make it heat or cool or stop heating or stop cooling. The "a lot" is actually in settings, so can be set even higher to be the limits.

But by default it uses "home" as reference. So if that it wrong it will be wrong.

It can use a different temperature reference, eg a BLE temperature sensor. There are a few models that work. That is probably what you want.

It also do a "Faikin remote" with a sensor that works with Faikin.

[sm-Fifteen]

@revk : But even if Faikin could get an external temperature reading, I don't think it could set the target temperature on the AC unit low enough to compensate for what the Daikin unit thinks is 19°C. The floor on most units is 18°C, so it's not like you can tell it to cool to 14°C (unless I'm wrong and you can).

[revk]

You may be right.

The Faikin can be set to try lower but it won't work if your unit has that as a minimum.

[bittylicious]

Yes, I already use an external temperature feed to Faikin for its smart control. It fails to cool further as the "Home" temperature is close to 18°C and Faikin can't set it below that.

@sm-Fifteen So, powerful mode will ignore temperatures and just cool (or heat) as much as it can? When I set it to powerful with the remote control, it does make a difference still so I think it does have some capability, if only there was a way to figure out what command triggers powerful as the in-built Faikin functionality doesn't work on this model.

Fan mode lets it settle to actual room temp. So it's not broken, but the indoor unit is in a weird wedge-type location in this room so wherever the temperature sensor is, it's probably sitting in a pool of cool air when the unit is cooling. Here's its location which might give you an idea:

Yes, it's not the best place unfortunately, and there's no space to blow air downwards to the air intake. I'll take any other bodge-recommendations if you have any!

[sm-Fifteen]

Yeesh, that unit has zero room to breathe. Not only is the room air temperature senskr not even visible (it's on the underside, there's some holes in the plastic shell to let air through), but jusging from the motion sensor and louvers not being lined up with their holes, it looks like the shell isn't even on properly.

Powerful mode, according to the service manual for my own unit, sets the target temperature to 18°C in cooling mode or 31.5°C in heating mode, and sets the fan at its highest speed setting (higher than the HIGH setting you can set with the remote control, this is the "HH/POWERFUL" speed). This is the target temperature, not the setpoint, so it disregards correction for hot air rising (which is usually a +2 factor, so a setpoint of 22°C will translate to a target of 24°C). If your unit sensor is stuck at 19.5°C, that will get you a 1.5°C delta, which should be enough to get it to reasonnably cool.

That's probably the best you can do here (based on our current understanding of how Daikin units operate and communicate), but it won't disregard the indoor temperature sensor like you would like. Faikin basically acts as a fancy wired remote control, it doesn't replace the "brains" of the unit.

[bittylicious]

@sm-Fifteen Thanks so much for your help here. The plastic shell is totally my bad - I thought it was just that I had not aligned the motion sensor when putting it back on after installing the Faikin (and didn't care) but I'll take it off and align it properly. However, I can say it's made negligible difference to how the unit performs.

Would you mind pointing out exactly where the air sensor is? If it's on the bottom, could it be the white box (which houses external blinds) causing the reading issues here? I know fixing the sensor won't solve airflow issues and nothing really will without a major reorganisation.

Thanks for the explanation about powerful - that may explain why it does seem to make a difference (not perfectly like our other indoor units, but noticeable). I'll see if there's any way to get powerful to work via the Faikin as it doesn't work out of the box. I presume there's no other way to control the target temperature directly?

[sm-Fifteen]

@bittylicious: I can't see it on your pictures, but my unit looks similar to yours and has the sensor on the underside, right below the power button or the remote sensor. It definitely looks like it would be blocked from what I can see.