I have a Lennox, 10 year old central air unit in my condo. The Air Handler Fan is not turning on as it's supposed to. I opened the unit and gave the fan a spin, and then it worked fine but still will not start on its own. I put the fan on manual and just letting it run, and that's keeping the house cool, but I'd like to get the fan to shut down like its meant to. I'm hoping a relay or something simple like that.