I have an older Samsung air condition unit which is probably 10 years old now. It will work perfectly for days on end but every now and again the compressor will not engage and I only get the fan. I only use the air con at night and it seems to happen when the outside air is typically simillar to the inside temperature. I set it at a constant 23°. When this happens and I try to reduce the setting lower to say 18° and it still will not engage. When the sun comes up and the outside temperature rises the air con comes on. Some nights it works fine.

 

Is there a sensor or something in the outside unit that can be changed or adjusted? I have swapped the remote control with one from another room and it is the same.

 The compressor is controlled by the thermostat.

 

Try  temporarly modifying  the thermostat such that you can stop and start the compressor at will.

check (have it checked) the pressure and fill of the cooling fluid.

Cut in/out thermostat may be on the way out.

Get it checked out

Sounds to me like the capacitor is going bad. Easy to replace yourself for about 500 baht. If you're not a do it yourselfer, call a tech.

3 hours ago, curtklay said:

Sounds to me like the capacitor is going bad. Easy to replace yourself for about 500 baht. If you're not a do it yourselfer, call a tech.

Agreed. That happened to me a while ago. Took 5 minutes to change (mitsub a/C). 

There are many qualified A/C repairmen in Thailand. Don't be such a cheapskate and find one.

3 hours ago, lagavulin1 said:

Agreed. That happened to me a while ago. Took 5 minutes to change (mitsub a/C). 

Just make sure you turn power off at the breaker first! ????

The outside box can have temp sensors. I was checking some outside wiring and do see temp sensors in it.

PTC or NTC sensors,  they change in resistance value when getting warmer /colder and therefor measuring signal.

If the connections/wiring of the sensors are corroded, the value also changes and therefor have an offset. 

As you mentioned the airco was running again when son comes up.

Of course in time, as your airco is 10 yo, their value can also change coz of age.

Cleaning connections and renew wiring connection can have positive result.

If not then replace the temp sensor(s) complete. 

AS above mentioned, there is an over/under-pressure and an over-temperature sensor on the condensor that may be going belly up.

12 hours ago, curtklay said:

Just make sure you turn power off at the breaker first! ????

Oh God. I didn't do it. Way too far out of my capabilities. Mrs E called in "The Man". ???? haha. 

On 4/18/2021 at 1:52 PM, curtklay said:

Sounds to me like the capacitor is going bad. Easy to replace yourself for about 500 baht. If you're not a do it yourselfer, call a tech.

That's my guess as well. Often the fan or comorsdor will run slow also before the capacitor fails completely. You can but a meter on Lazada that will measure capacitors as well as voltage, current, resistance for a few hundred thb. 

Yes problem solved thank you all for the advice. I called someone to do it in the end. It would have been relatively easy to do but I thought if I bought one and then it wasn't the capacitor I would have wasted 500 baht. All seems ok at the moment I shall reserve judgement in saying its fixed 100%, as the problem has been intermittent. Fingers crossed.