that's not the only reason your utility bills keep going up. older a/c systems lose efficiency and use more electricity to operate. if your electric bill is high, talk to your neighbors to see if it's just the average cost for your area or if something like an old a/c system could be driving up your bill.
strange noises could be a sign that your a/c system needs repairs, or they could just be noises that it has always made. in addition to considering the cost of repairs versus replacement, you should know that a/c construction and design has improved so that new systems feature very quiet operation.
with warmer spring and 