I have a 2 year old 4 ton American Standard HVAC unit and the blower fan will not turn off no matter what I do. This problem happened at the same time last year and the tech cam out and replaced my thermostat and all was fine. I have troubleshooted the thermostat and this is not the problem. I have reviewed other posts online with similar problems so I went into the attic and removed the panel cover to find that the code light was blinking 4 times. It states on the panel cover this means the limit switch is to blame. Where is the limit switch and what does it look like? I think I know what it is, but not sure. I located a button type part with 2 screws and 2 wires attached to the blower, is this it? I removed the wires and removed it to see, but nothing that helps me id it for sure? Any help?