1998 base model,3.1 litre. about 134,0000 miles. still the original a/c and it always blew like alaska from the get-go. now it is an unusually hot summer, but especially from a start-up i notice it doesn,t put out very cold air. now and then it will put out ice cold as before. the engine temp gage has been normal. does this sound like the beginning of the end of the compressor?