Mine downstairs went out last week and I should have changed them both as upstairs started having problems yesterday. My AC guy said he has been changing them everywhere! If the thing looks puffed out and ready to blow the lid that is probably your problem.
My friend said they used to last 10 years, but cheaper parts that are coming in can last half that. In fact I bought a extra one just to keep on hand.
My chillers have been running and my electric bill is going to **** me off for sure.