Maintaining equipment is like maintaining good staff. You can't avoid it, and you need to keep up with it!
When you run a restaurant you are hopefully beyond the stage when you think you can do it all yourself. Maybe you are even beyond the belief that your staff should have monthly cleaning log that includes maintaining equipment. Like any good tool is remains good when you maintain it, and that may mean calling a HVAC company to set up a quarterly cleaning and maintainance plan; and a restaurant equipment company to set up a quarterly cleaning and maintainance plan. They will detect issues that will stop you from closing because a piece of equipment is down. It's an insurance policy that truly gives back.
Consider a quarterly plan. Penny wise, pound foolish as the idiom goes!