The good news is that winter is half over. The bad news is that winter is only half over. Don’t leave heating to chance. Instead think “furnace maintenance” — an ounce of prevention beats a pound of cure, and a chilly wait for an expensive repairman. Here are a few things that’ll help. First change the filter. During heating season, do this monthly and — to save money — don’t buy them one at a time. Buy a whole case, and save money two ways — on the price and on your energy bills. A furnace heats more efficiently and runs less with clean filters that are changed often. Other mid-winter furnace tips? Check your owner’s manual for proper guidance. Turn off the power, vacuum the blower compartment, check tension and condition of the blower fan belt and lubricate fan-motor oil ports with a few drops of lightweight electric motor oil (do not over-oil or use automotive oil — both practices are bad). A little mid-winter furnace maintenance gives a lot of peace of mind.