Faulty Circuit Breaker?

I have been having trouble with my AC unit. Occasionally, the breaker flips and I have to reset it. I have had an AC company come out to look at the unit 5 times now and they still can not pinpoint an AC problem. I am starting to think it is the circuit breaker itself. How can I determine if the breaker is the culprit and needs to be replaced? The AC company is only interested in selling me AC parts. Today they decided that I may be leaking freon!!!! The system cools just fine when it runs and it will run for days without flipping!!

Try posting in the Electrics outside UK!

If I thought I had a faulty MCB, I'd just fit a new one. SP MCB is about £5 over here.

It's very unusual, though. I've heard the Chinese manufacturers, including counterfeit, can be very poor quality. I've known UK manufacture, such as Crabtree C50, run faultlessly for 40 years.

I wouldn't consider the MCB to be faulty before I'd compared the rating of the MCB with the rating on the AC unit, verified that there was no other load on the circuit, had a look for signs of overheating including damaged cables or rainwater/condensate causing a short.

I might also try a clamp meter to look at the actual current draw and compare to the AC rating; and I'd look up the manufacturer's documentation to see if they recommend a surge-resistant "slow-blow" type C or greater MCB to accommodate start-up surge.

What current does the maker's rating plate on the AC unit say, and what rating and type is your MCB?

What other loads are on the circuit?