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The apartment I rent has multiple Toshiba AC units used for both cooling and heating. I'm sometimes annoyed at how they sometimes seem to work weirdly - heating the room to absurdly warm despite me setting a low temperature, or vice versa - but I'm wondering if the problem is actually in my misunderstanding of how the remote control works.

The remote control has a display showing the set temperature (and mode, fan speed, etc.), but the AC units themselves do not, so it's not obvious what temperature it's aiming for, or what temperature it's currently measuring.

We are usually sharing one remote control for multiple AC units and I wonder if that's my problem. I assumed that when I press the down arrow and the display now shows e.g. 24 °C, auto fan speed, heating mode..., the remote sends a command to the AC that says "set temperature to 24, auto fan speed, heating mode". So it wouldn't matter that a minute ago I used the same remote to set the temperature to 26 at another room.

But what if the remote actually sends a command saying "decrease set temperature by one degree" (i.e., only what button I pressed)? Then the displayed temperature on the RC display and the set temperature of the AC unit could easily get out of sync. Is that how it actually works?

(Side note: the temperatures I'm quoting may seem ridiculously high. I assume this is because the temperature sensor is in the AC unit near the ceiling, so to achieve a comfortable 22 degrees in the room I need to set something like 25, though I've never actually measured the temperature near the ceiling. Or maybe the regulation is just totally miscalibrated.)

The AC unit is Toshiba Carrier RAS-B10SKVP-E and the remote is Toshiba WH-H04JE.

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    The specific model of HVAC unit you have might be useful for finding this out.
    – FreeMan
    Commented Nov 16, 2022 at 16:03
  • Good luck with that. I haven't seen one yet that will tell you what it does with remote sharing. The "emergency operation without a remote" is commonly documented, and operation with a remote as they expect you to use one is commonly documented, but remote sharing between heads is not spoken of.
    – Ecnerwal
    Commented Nov 16, 2022 at 16:10
  • I imagine someone must have decoded the infrared signaling, as "universal" remotes exist.
    – vashekcz
    Commented Nov 16, 2022 at 16:29
  • most remotes, esp IR ones are more like dumb keyboards that send the keycode, not higher-level instructions like temp set points. The "codec" that most use (NEC) isn't great for sending arbitrary data, it's focused on noise-overcoming id codes, which makes sense given the typical application.
    – dandavis
    Commented Nov 16, 2022 at 19:35
  • Interestingly, this remote costs ten dollars. That would turn me around on remotes, as custom console and display designs are actually a very costly part of consumer products. If they can get China to fart out these remotes by the million for ten bucks, then golly just provide a place where it snaps in and then auto-win. As far as being a dumb one-directional IR remote, disagree - it is clearly transceiving since it indicates set temperature. Commented Nov 17, 2022 at 3:34

3 Answers 3

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It's really best to use one remote for one head with these systems, rather than what you are doing sharing one remote among several heads.

How they work when you don't is generally not documented, so your question as to how it works when not using one remote per head is hard to answer accurately - but you can perhaps work around that by shutting down and turning on and setting temperature from that point. As expected, I don't see much helpful for running a bunch of heads with one remote in your model's manual, but they do offer a way to control 2 heads with one, or to have two controllers that only operate one head when two heads can see the same signal.

Page 6 of this manual offers (barely, and refers you to the dealer to set it) a method to use one controller for two units by "remote switching" without any further info about it. Page 19 documents "temporary operation without the remote controller" but does not reveal what setpoints it uses. The "Service Manual" does say how to enable remote switching on page 50. You cut a jumper wire in the battery compartment on the controller, then reset the head unit and power it off with the remote you cut the wire in. That sets the head to "B" the remote can switch from A to B as follows "Even after the jumper wire has been cut, switching between A and B is still possible by pushing the CHECK button and FIX button together."

Also, get some ceiling fans to push warm air down if your heat pump heads don't deflect air downwards adequately via their own louver settings.

As for the set temperature not being the temperature you are aiming for, that's typical and normal, since virtually all of them measure temperature at the head, and the head is normally located above the space if intended for cooling as well as heating - but louver settings or ceiling fans can help to minimize the gradient. Page 51 of the previously linked service manual details a crude means of adjusting by cutting jumper wires.

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I would start with the user manual, which I found here: https://www.manualslib.com/download/579202/Toshiba-Ras-B10skvp-E.html

On page 5 (page number a the bottom of the document, not the page number in PDF) it says

• If two indoor units are installed in the same room or adjoining rooms, both units may start and stop at the same time when the remote controller is operated. This can be prevented by setting the switching function so that each indoor unit is operated only by the corresponding remote controller. • To use the remote controller switching function, contact the air conditioner dealer or the installation company.

It's not clear where/how to set this function, or whether or not that means you would then have 2 remotes. It SOUNDS like you could have up to 2 units, an "A" and "B" unit, which would talk separately with 2 remotes.

So then what I did was download the service manual: (https://www.manualslib.com/download/1348610/Toshiba-Ras-B10skvp-E.html) and it appears that the remote is indeed transmit and receive, so it seems to me like it should be receiving the current temp from the AC unit. Looking at the block diagram on page 25:

enter image description here

I think I would run some tests. Set one unit to the lowest temp possible, and the other to the highest temp possible. Then go back to unit 1, and then increase the temp by 1 degree, and see if the remote suddenly reads the "correct" temp that you believe the unit is set to.

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Had similar question. Using two remotes was able to confirm that the remote sends the temperature value (not just +/- 1) for Mitsubishi MSZ style heat pumps. I imagine Toshiba is similar. If the cassette unit has apparent temperature based activity you can manipulate the temp setting with one remote and see if the other remote is consistent to test the behavior.

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