AC problems: where is the thermostat of a wall-mounted AC?

[siam2007]

Gd day all,

having problems with one of my AC's, a common wall-mounted DAIKIN. It seems the thermostat is either misscalibrated now or maybe dirty and can not estimate the proper outside temperature, which makes it turn into "Fan-only" mode even when it is very hot inside the room, as it thinks it is actually a lot cooler than it is. When I open the front hood where the filters are, I can not see anything that looks like a thermostat, and it seems there is no other flap that you can open where the thermostat could hide.

I am aware that I may eventually need a technician, but considering the fact that many Farang here had abysmal experiences with AC-technicians, I would at least like to have a look first and then alert my landlord in case it is a bigger issue and I can not solve it.

Thanks

[lopburi3]

I do not have that model but on most units it will be somewhere in front of the cooling fins in the path of air through them and just look like a loop of wire and maybe plastic holding it. Often under the filters on one side or the other. Does it actually start cooling again if you lower the set temperature? Or does it never get cool enough during the day? Is unit being serviced every six months (cleaning)?

Thermostats do not estimate outside temperature. They just measure what the temperature is at there location.

[KittenKong]

As mentioned, the sensors look something like this

and are usually mounted near the rest of the electronics.

Lots of pictures here:

<https://www.google.co.th/search?q=air-con+temp+sensor&tbm=isch&tbo=uimgrc=_>

Lack of regular cleaning could easily stop the thing from working correctly.

[siam2007]

I do not have that model but on most units it will be somewhere in front of the cooling fins in the path of air through them and just look like a loop of wire and maybe plastic holding it. Often under the filters on one side or the other. Does it actually start cooling again if you lower the set temperature? Or does it never get cool enough during the day? Is unit being serviced every six months (cleaning)?

Thermostats do not estimate outside temperature. They just measure what the temperature is at there location.

thanks for the replies so far, well the "thermostat" on your picture does not look exactly like me as a non-expert would have expected. ERMMMMM {~_~}

The filters are clean, I clean them regularly.

It seems it does not recognize it when I am lowering the set temperature. It basically acts the same no matter if I set it to 18 or 28 degrees.

Once it actually runs, it is cooling as usual. Only that it stops after a few minutes and goes into the "Fan-only" mode for some more minutes before it starts the cooling mode again

[lopburi3]

Have you got it set to "dry" mode rather than "cool"?

[bankruatsteve]

The filters are clean, I clean them regularly.

It seems it does not recognize it when I am lowering the set temperature. It basically acts the same no matter if I set it to 18 or 28 degrees.

Once it actually runs, it is cooling as usual. Only that it stops after a few minutes and goes into the "Fan-only" mode for some more minutes before it starts the cooling mode again

The filters do need to be cleaned but that is not what REALLY needs to be cleaned. You might be surprised to see the gook that is cleaned out by professional cleaning. That is what is needed at least twice a year for busy A/C.

[KittenKong]

thanks for the replies so far, well the "thermostat" on your picture does not look exactly like me as a non-expert would have expected.

My picture was of a temperature sensor. There is no thermostat as such. The sensors merely transmit an electrical signal to the logic board which then decides whether to switch the cooling circuit on or not.

These sensors are very cheap and dont last forever, not least because they generally have to be removed or relocated when the unit is properly cleaned. This is why they are usually simple plug-in devices that can easily be replaced.

Not all sensors look exactly like that one but you should find images of most of the usual types in the link I posted.

[Jdietz]

http://www.mtbmechanical.com/if-your-air-conditioner-keeps-shutting-off-read-this

There are several factors that typically cause short cycling. They are listed below.

* Compressor problem- Your a/c compressor is the engine of the refrigerant cycle. It generates the pressurized conditions through which the refrigerant both absorbs abd dissipates thermal energy. Often, your compressor is a sealed component preventing dust and debris from damaging it's moving parts. If the compressor is overheating or is worn out, this will often result in the system shutting off frequently.

* Low Refrigerant- The refrigerant level in your a/c needs to stay at a consistent level for the system to work properly. If your refrigerant level falls to an inadequate level, you will experience poor cooling performance and energy efficiency. This can then lead to short cycling.

* Frosty Coils- Inside your air handler is an evaporator coil. This cools the warm air that is drawn in from the inside of your home. If you have an airflow issue such as a clogged air filter, frost can build up on your evaporator coils. This again, can lead to a short cycling issue.

[singa-traz]

I had a similar problem, and replacing the sensor solved the issue.

[noise]

The filters do need to be cleaned but that is not what REALLY needs to be cleaned. You might be surprised to see the gook that is cleaned out by professional cleaning. That is what is needed at least twice a year for busy A/C.

Bankruatsteve is correct. You may need a professional power wash of the evaporative coils. Moisture and dust coagulate on them and build up over time. It is amazing how well the air conditioner works after a cleaning if it has not been done regularly.

A good technician will bag the unit on the wall and all the dirty water will be channeled into a drum with no mess on the walls or floor.

They will also check refrigerant and cooling when they finish.

Affects your electricity bill, also.