AC irregularity

Your regular mechanic is probably the problem. The symptom you are having is usually because the refrigerant is low.

The normal way the system is charged, they removed ALL THE REFRIGERANT on the car (with a machine), and then add in the proper amount. If your mechanic didn't do that, then low refrigerant may still be an issue.

 

Sounds like the doors aren't operating properly in the HVAC system . I have an 07 that does similar .I have the damper door locked in AC coil open position . Don't know if I'll get to the actual motor fixing . As heats almost never needed.its a bunch of crap to get at the black box motors . What you want to do here is when your system starts to not cool pull over lift hood and check the fat silver hose is it still cold .? If so you're making cold you're just not getting air across the cold . If it noticably warm the compressor not making cold . If standing sitting in driveway . You attach a can with a gauge on that fat silver hose and see very close to 100 psi . You pretty full now cycle AC and see it drop to about 37 psi and that hose is getting coooold. You probably so close to being full that that's not your problem not saying it cannot be but uhh. Not likely. I haven't signed any refrig in my 70 year lifetime so far. And all my AC systems that I own are capable of blowing snowflakes out the vents if I desire. I require temp control or I'll die. Purdy simple. 9 have certs to handle all gasses in most systems. Weighing is good protocol for the masses so that mistakes can be minimized. That's a fact.

 

This may be SO EASY.
Check to ensure your inverter cooling water pump/system is functioning properly.
A typical symptom of this pump failing to provide adequate flow is intermittent operation of the AC. The AC compressor is powered by the inverter. The inverter is cooled by the inverter cooling water pump system. If the pump is failing, the inverter starts getting warm. One of the first things that will happen to protect the inverter (with no alarms or warnings tho) is that it will cut off power to the AC compressor. Once the inverter cools (like if you shut the car off for a while) it will again send power to the AC compressor. Many people and many thousands of dollars have been spent chasing tails in the AC system when the true problem is a small electric cooling pump located behind the driverside headlight.

Check it out.

 

Sounds to me like your mechanic doesn't know it's variable pressure AC system and added too much refrigerant and now your AC compressor is overheating and triggering a thermal shut down switch. If you present your situation to owner of the shop your mechanic works at they'll likely realize they're at fault and replace your compressor at no charge. But make sure you present your situation in a way that they don't blow you off or dismiss you because you make AC replacement cheaper than them having to hire an attorney to deal with you if they won't fix it.

 

Something simple; check the radiator fans are turning. That should toggle-on when the AC button lamp is green. I would guess that your mechanic would've noticed that; but he doesn't know how to properly fill a variable speed AC compressor either.
The second question is, did he use the right stuff????

 

That is a fact make certain you have cooling fans and an inverter pump operating usually just putting your hand on it no Inverter pump very quickly no AC no cooling fans very warm AC

 

Most common cause of that is an overcharged system when the pressure is too high it's safety switches off. This is the most likely cause but diagnostics are required. I can't diagnose from here

 

I think this is a real possibility if the OP does not drive long distances. Just long enough for the car to get hot and lose AC, but not long enough for the red triangle to come on before stopping. This would not be able to be diagnosed by a normal mechanic, unless they are looking for a failed pump and not an AC issue