The usual agency move is a page for every DFW suburb. Google has seen that movie. HVAC companies need pages for the jobs that pay and the markets they actually run — not a generator. Here is the standard NOBLE uses.
Service pages before city pages
AC repair, installation, and furnace pages usually matter more than a tenth suburb. If the homepage is the only URL, start there. City pages cannot save a site that never names the job.
Dallas vs Fort Worth is a real split
Dallas HVAC is neighborhood density. Fort Worth HVAC is distance across a wide city. Those two pages can both exist. Plano only exists if the copy is about Plano — competition, how people search, where the trucks sit — not Dallas with a find-and-replace.
What unique copy looks like
Landmarks people actually use. Driving reality. Who you lose jobs to. Example searches without fake volumes. A diagnosis example. If you cannot write that without inventing it, do not publish the URL.
Internal links
City pages should link to the HVAC service page, Local SEO, the matching location page, and a useful resource. Exact-match “HVAC SEO Dallas” in every sentence is stuffing. Natural anchors are enough.