Troubles with air conditioning

07.06.2011 16:03

Last week the remote on my Airwell air conditioning unit stopped working. In a pure Murphy-inspired coincidence it failed on the exact same day when a service man was scheduled to come perform the yearly maintenance. After some embarrassing moments when I couldn't get the thing to start he got it going with manual controls.

I quickly verified with a camera that the remote control is actually transmitting, so the problem was obviously in the unit itself. He didn't have any spare parts with him so I decided to look into the issue myself before calling the service again and he was kind enough to show me how get the cover off.

Airwell air conditioning unit with the cover removed.

With the cover removed the location of the IR receiver board was immediately obvious. Right next to some shoddy wiring work that made me immediately reach for my soldering iron and shrink-tubing. I know electricians despise using a soldering iron, but you do not connect wires on a kilowatt-range equipment by merely twisting them together.

IR receiver board from an Airwell air conditioning unit.

Any way, this is the so-called receiver board. In fact it holds four visible diagnostic LEDs, one high-intensity IR LED and one integrated optical receiver module, all on independent circuits. The receiver also has a tank capacitor on its supply line and a common-collector amplifier on its output.

Nothing was obviously broken and after connecting the receiver part to 5 V supply it sort of worked. However the output signal wasn't swinging rail-to-rail as it should be and it seemed to be affected by mechanical stress. None of the soldered joints seemed faulty upon visual inspection, but after reflowing them the problem went away.

I wonder what the IR LED is used for? It can't be for two-way communication with the remote control, because the remote control only has two LEDs and no receivers (at least that's on the model I have). When the unit was working again I checked with the camera and the IR LED is indeed active and seems to transmit something whenever the receiver receives a command from the remote control. Perhaps it is for synchronization if multiple units are installed in the same room?

IR burst sent from air conditioning remote control.

By the way, the remote control emits a burst of data whenever a key is pressed. The packet is quite large, taking more than 200 ms to transmit. This is several times longer than in ordinary, say TV remotes, so it looks like it transmits the entire state, not just individual commands.

Posted by Tomaž | Categories: Life

Comments

You'd make a perfect husband! :)

Posted by Nace Oroz

"By the way, the remote control emits a burst of data whenever a key is pressed. The packet is quite large, taking more than 200 ms to transmit. This is several times longer than in ordinary, say TV remotes, so it looks like it transmits the entire state, not just individual commands."

my theory it IS for synchronization as
some remotes have lcd displays will all the states displayed

you can change multiple functions with them and in case the synchro is not complete (in my case no beep from the ac unit) the next time you success fully change something (and there is a success beep) all settings are changed in ac to the settings you have on your lcd remote

Posted by someone

Hi Tomaž,

This week, I had exactly the same problem with my Airwell air condionner, no command from my remote control.
By chance, I found your post on the web and I have applied the same solution, reflowing of the board and you know what:
it works!!!!!!!!
So, thank you for your kind explanation and continue to post interesting remarks like this one.

DIDIER

thanks to you I was able to run my air conditioner airwell ..... I did a reflowing the board IR receiver and now it works perfectly

Thank you for the blog post! i had the exact same problem with my aircon yesterday. and it really works by soldiering the behind part of the signal receiver board!

Posted by maggie

Hello Everyone!! I've got the same exact problem but resoldering/reflowing the board didnt help :/
At first i was so happy to see that this solution help that many people but when i tried it ,i couldn't get it working.
I checked the cable as well and it's working 100%
I guess the problem is in the mainboard of the Air Conditioner because when the receiver board is plugged in and i try to move it's cable a litle bit the red LED turns off and on, or all the other LEDs turn on and off for a second. Not sure where's the problem but i'll keep searching.
Please help if anyone knows what to do!

Man, you made my day !! I just had the same problem but wouldn't have had the idea to re-solder as soldering looks ok visually. I gave it a try thanks to your blog and it worked :-)

Many thanks !!

Posted by Guilhem

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