View Full Version : Samsung AC indoor unit MH035FPEA is turning on and off automatically

17-07-2017, 02:33 PM
My Samsung AC indoor unit is turning on and off automatically all the time, without any apparent reason and without giving any error.
Other indoor units are working ok but because this is a multi-split installation and I cannot disconnect this unit independently I had to turn off the entire AC power.
Here's a video showing the unit turning on and off automatically:

The indoor unit model is Samsung MH035FPEA.

I would appreciate if someone can give some advise how to proceed.

I would expect there should be a way to reset the interior unit using the remote control.

Thanks in advance.

The Viking
17-07-2017, 04:19 PM
First thing to check is that it isn't due to interference, cover the IR sensor (translucent bit on the underside of your unit) and see if the issue continues.

If that didn't solve it, have you got any central time switches or other interfaces connected to your system? WiFi control?
(Samsung units can be fitted with an interface card, for example to start/stop the unit as doors are opened or to operate them via a central on/off switch or time clock. A poor connection in a connector there could cause similar issues to what's on your video)

It is also worth opening the cover on the outdoor unit, there you will see 2 small displays side by side scrolling through the addresses of the indoor units it can "talk" to. Can it see as many indoor units as you got installed?
Also, after you looked at what units it can see, below those screens are 4 buttons, press and hold the one marked K3 for 5 seconds. This is the global reset and the system will start by itself after a couple of minutes.

If none of the above helps then it is time to call your installers back in, or your friendly AC engineer...
http://www.samsung.com/pt/support/ should also be able to help.


23-07-2017, 09:47 AM
Thanks for the hints.
However it didn't solve.

First I checked if there was some interference by covering the IR receptor, but the behavior is the same.

Then I checked the outdoor unit.
The display shows the following:
- right display: 2 zeros fixed
- left display: it switches rapidly (every 0.5 second) between 01, 02 and 03, check the video:

In the video it's had to see it correctly due to the display refresh rate, however, despite what may seem to happen in the video, the right display is not blinking, is fixed at 00. Only the left display is switching between 01, 02 and 03.

I have 4 indoor units so if that display is supposed to show the connected indoor units, then one is missing.

Then I pressed the K3 button and after some seconds, the left display stopped and was showing F6 while the right display was showing 44.
After 10 seconds or so, it went back to the same initial state. Nothing happened on the indoor units.

Since I cannot disconnect this individual unit, I suppose I cannot perform more tests.

Do you have any other idea?

The Viking
23-07-2017, 12:47 PM
So the outdoor unit is only seeing 3 indoor units whilst we should have 4.
That is good, it point us towards where the issue might be.
Most likely you got an issue with the communication wiring and looking closely at your video I spotted one issue. The cables to F1/F2, the communication cables, should not be run as part of a multi core cable with the mains. They needs to be run separately and if you follow the installation manual "300mm away from any source of interference". OK, here in Europe we would never guarantee that the cables are 300mm away from mains cables, speakers, light fittings and so on, we would used screened cables instead. Comms cables should also never go through any switches.

After the comms network been sorted out (for ease of installation use 2 core 1mm screened cable with the screen earthed in the outdoor unit and in the outdoor unit only), you will need to "recommission" the outdoor unit to make sure it is communicating with all indoor units. If you give us the model code of the outdoor unit I will send you the information on how to do this.


23-07-2017, 03:35 PM
Thanks for the quick answer!

The outdoor unit is the MH068FXEA4.

The Viking
23-07-2017, 05:28 PM

If you follow this link HERE (https://drive.google.com/file/d/0B3dT89cZx1PBaGRoek9kd0RlbFE/view?usp=sharing) you will find the relevant part of the install manual.

Just upgrade the comms wiring with the power to the unit OFF and then follow the manual. (My personal preference is to manually address the indoor units as I then know which unit got which address, making future faultfinding easier but the automatic addressing does work)

EDIT: If you select to manual address, ensure the units are addressed 0-1-2-3 as in the example.


The Viking
23-07-2017, 10:52 PM
And I forgot to add...
If you in the short term do want to turn one unit of, isolate that unit and remove the cables from the F1-F2 terminals in it (but don't leave them loose, put the loose cable ends in a terminal block to make them safe). Following the manual I posted above set the outdoor unit up to run with 3 indoor units.


24-07-2017, 03:27 PM
Thanks for the information!

But I have one question: how do I know which F1-F2 terminal to disconnect since are more than one pair?

The Viking
24-07-2017, 04:50 PM
To make sure you get the right pair just disconnect in the indoor unit, only one set there.