Carrier central air conditioner shuts down all the time after only a short time

by Kate

Room temp taken 26 cels air con on auto runs 1 hour sometimes less shits down and turns right off I have o climb up to the main switch to turn it off them on. this unit has been check for gas and the installer they tell me they don’t no what’s wrong with it they tell me its an airo dynamic problem as it is 2 feet across from a brick fire place, I say it was going fine when I purchased it.

So why after 2 years would it suddenly develop this problem? Don’t know the model number off hand but the unit is only 3 years old and it has been ongoing with the same problem for 2 years. And not resolved with the dealer. Heating is fine.
Can you advise?
Kate