My window air conditioner unit keeps tripping the circuit

Question

I'm here asking for advice on next steps, please.

We live in the desert and it's only 109 right now. I say "only" because in previous years it can get as hot as 122-123 degrees. I'm noticing a pattern with our air conditioner unit we had professionally installed in our garage to keep it reasonably cool. Whenever it gets near 110 or above outdoors it trips the circuit. It's not a window unit but it's the type of unit where you have to actually cut into the wall to install for a custom fit.

Due to previous issues with the circuit tripping, we had an electrician come over to designate an entire circuit just for this air conditioning unit. The goal was to prevent excessive power coming from the circuit to prevent the ongoing problem we keep having: failure. However, when it gets over 108 degrees it trips.

This has happened for two summers in a row and has occurred after we had electricians designate a single circuit for this wall unit.

My questions are, could the electrician have designated a heavier duty wire to prevent this from happening? Why is this an issue especially after we hired a professional. I'm going to contact him again and ask him to rectify this. But I fear he might be incompetent. Hence, why I'm here asking for input. We paid good money for him to designate this circuit and it becomes completely useless when it gets very hot outside.

Meanwhile we have two A/C condensers blasting all day to cool off a two story home in Palm Springs. I know they are on their own designated electrical connections. It just seems ridiculous that we can't keep a garage at around 90 degrees (because we have chemicals (e.g. paint thinner, canned paint, spray paint, etc) and fridges in there that we don't want to overheat in 110 and up heat.

Addendum: For stats on the unit itself I am providing a link to the item we purchased as it has all the specs there:

https://www.walmart.com/ip/Koldfront-Wtc12002wco115v-12-000-BTU-115-Volt-Through-The-Wall-Air-Conditioner-White/146481293

Answer 1

Well, lots of churn in the comments but we know a couple of things.

The circuit is dedicated, at least 15A, and was installed by a pro.

The AC unit apparently draws 10A. ( Thanks @Ecnerwal )

We don't seem have the ability to measure draw with a kill-a-watt or ammeter.

So, probability-wise, it's the AC unit gone wrong. Compressors bind up and cause high draw. (Sometimes short-lived, but enough to trip the breaker.)

After that, it might be the breaker. They can wear out and trip more readily over time. If it's a GFCI breaker (ie, it has a 'test' button), that might be an issue.

It might be the wiring itself (loose connection, mouse chewing wire, etc), but this isn't that common.

My best suggestion is to buy a replacement unit from a place with a generous return policy. If it runs successfully, then it was the original unit. And you have a replacement already.

If that fails similarly, get someone looking at the electrical supply. It's possible that the electrician was incompetent, but not really likely, as a home run wire is just about the simplest thing they do. If the nameplate on the AC unit said 10A, then a 15A circuit is entirely appropriate, so upsizing wires and breakers wouldn't be a natural strategy.

FWIW, fridges create heat when running, so you aren't helping matters by running fridges. (Especially if they're cranky old ones, as often find their way into garages.)