Extreme Heating and Air Conditioning is a home-based business serving McHenry, Cook and Kane counties since 1985. The company installs and services air conditioners, boilers, humidifiers, water heaters, thermostats and furnaces. All of its technicians have NATE (North American Technician Excellence) certification. The company also provides 24 hour emergency service. Printable coupons, such as 25 dollars off any service call, can be found on the website.