Regardless of the nature of your business, being seen on the internet is a highly recommended way to getting more calls from paying customers. This includes customers who are not looking for you specifically, yet they need your services. People who would usually go to your competitors would now be calling your HVAC company instead.
With a strong online presence for your HVAC company, consumers will see your company on the first page of the results. That will lead to more calls for you because very few people actually go to the second page.