Last year my highest power bill was $320. This month my bill is $598. My outdoor unit is running around the clock. The inside temperature reaches 84F around 2-3pm. It's putting out cool air, but it does not seem to be as cool, or as strong (the air flow) as it was in the past. I called a local HVAC company last month for a diagnosis. He came out and said my coil was probably clogged up with grass clippings. He sprayed it out with the hose. Then he put gauges on it and said everything was fine including the refrigerant levels. I got a bill for $150 but the problem was not solved. Since then I have cleaned the indoor coil. That did not help. I used a fin comb to straighten any that had been bent. No change. The compressor does not seem to have any issue starting, and seems to run continuously. What can I check for now? The unit was installed in 1998 I believe.