I have an older A/C unit that will not blow air. The compressor turns on and the copper tubes gets cold....but the fan/blower does not turn on and does not blow air, it only lurches and tries to get going occassionally until the compressor shuts down. I've set the thermostate fan control from auto to run and I can actually hear a lurching/cluncking sound through the vent system as the blower/motor tries to kick on. I've replaced the run capacitor (10 microfarad/440volt)...but still the same problem. What should I do? Help...it is over 90 degress!!