Strange temperature behavior of Panasonic S-100PF1E5A with CZ-RTC4 remote

[rndm2]

Hi,

I have a central AC in my new home and faced a problem.

In general, the air-conditioner ignores the temperature that is set on the remote controller (in auto or cooling mode):
1. In auto mode, if I set the temperature on the remote control to 25°C room can be 26°C or 26,5°C, and it doesn't start cooling it.
2. In cooling mode, if I set the temperature to 25°C, it cools indefinitely unless the room becomes 23°C or even lower.
I am talking about the living room, where the remote itself is located.

For example. In the evening room was 26,5°C. On a remote controller, I set the mode to cooling and temperature to 25°C and went to bed. In the morning, the room temperature was 22°C, and it was really cold.

We are unable to get 25°C in the living room no matter what we do with the AC remote. It is always 23°C or 26°C.

---

What I did:
1. I called local engineers. They said, "this is how the system works; we can't fix this." They even didn't know that I could change the reading from the sensor to the remote itself (parameter 32).
2. Cleaned all filters. Now it can make me freeze much faster
3. Switched to the thermostat temperature sensor (parameter 32 "Wired remote controller sensor" on remote). It got even worse after this.
4. Checked all parameters according to my knowledge of how it should be. Almost all of them are defaults. Device type and capacity seem to be set right.

The device is S-100PF1E5A with CZ-RTC4 remote.

I am new to air-conditioning, but I am an engineer, so I'll figure it out, but I have some questions:
1. What part of my system decides when to turn on cooling and when to turn it off?
2. What if I buy something like this https://www.amazon.es/gp/product/B08DBZ35NJ/? Will it work with my AC? Will I be able to fine-tune cooling?
3. What else can I check in order to get the current system working as expected, assuming the main unit is mounted above the ceiling in my bathroom?

Thanks!

[seanf]

Sorry I'm not familier with the system you have but,

Is the cold air only supplied to the living room? Or is there ducts to other areas in the house.
Does the return air to the cooler come only from the living room? Or is it taken from the roof void, or from multiple rooms.

[rndm2]

Sorry I'm not familier with the system you have but,

Is the cold air only supplied to the living room? Or is there ducts to other areas in the house.
Does the return air to the cooler come only from the living room? Or is it taken from the roof void, or from multiple rooms.

The system is closed: it doesn't get fresh air from outside.
Cold air is distributed more or less evenly around the house. Actually, it is a big apartment, not the house-house itself.

[seanf]

The system is closed: it doesn't get fresh air from outside.
Cold air is distributed more or less evenly around the house. Actually, it is a big apartment, not the house-house itself.

So is the intake air to the cooler taken via ducts from all the rooms, or is it only from one room, or maybe just from the roof void?

[rndm2]

So is the intake air to the cooler taken via ducts from all the rooms, or is it only from one room, or maybe just from the roof void?

I will inspect it on Saturday.
But yes. It has an inlet and outlet in every room. So I suppose it mixes air then

[seanf]

Had a wee look at the service manual for the controller.
It looks like you can view what the units thermistors are measuring, maybe your able to check them against your own thermometer's reading.
Also looks like there might be thermistor offset settings as well.

The one I was looking at http://www.icglimited.co.uk/library/...e%20Manual.pdf