I have a Lennox Hs16-261U-4p Air Conditioner. It worked fine last summer. I turned it on today and it starts right up. However, the fan in my RHEEM furnace is not coming on. It does not work on the auto or fan setting. The furnace worked fine all winter long. I am told the AC unit may need to be reset. Is this a possible way to fix it and how do I do that? I do not see a reset button on the outside.