First of all, I live in Dubai, UAE.

We've been living in our current house since 2003 and it was not like this before. Basically, when the outside temperature goes above 43 C or so, my room's central A/C stops cooling (but the A/C fan continues to run) and starts blowing normal temperature air. The cooling in the other rooms in the house remains fine though (the other rooms have their own A/C compressor and thermostat). I've had this problem for the past 4 years/summers and the maintenance guys have been changing parts and whatnot over the years which result in no improvement. When the outside temperature goes below 43 C or so, cooling starts again.

Recently, the maintenance guys cleaned the outdoor unit, indoor unit, replaced the capacitors, and the contactor.

I found a thread that deals with the exact issue I am having but no solution is provided in the thread: My Central A/C doesn't work when it's too hot outisde...HELP

When it is hot outside, the compressor may turn on for like 30-40 seconds but then turn off again.

Any ideas?

 

I'm adding in the temperature conversion so posters won't have to look it up:

43C = 109F

 

I had an old Carrier that shut down a few times when the temps were over 100F. It had started just after my spring tune up, where additional refrigerant was added. Turned out that the charge was too much and the added pressure when it got really hot was shutting the compressor down on thermal overload. I'd suggest having the charge checked when it's nice and hot outside.

 

They need to......
1) check the refrigerant charge. Too high of a charge will cause the unit to overheat.
2) check the line voltage and current draw when running. A voltage sag will cause the unit to shut down.