Every year, you see signs that winter is coming. You may prepare yourself for the approaching season in many ways. You might change over your wardrobe to include warm and cozy clothes. You may put an ice scraper in your car and make sure your shovels are handy. You may begin to winterize your house by turning off the water to the outside hose bibs and putting away your hoses. Do you think about your HVAC unit before you have to turn on the heat? Unfortunately, many homeowners do not and find themselves stuck without heat just when they need…