What follows is about the Google Ads account, the one billed per click. How much of the budget goes there is a separate decision, and it comes first.
What changed in the account since 2023
Enhanced CPC was retired in 2025, announced a year earlier, so the manual bid with a nudge on top of it is gone. AI Max for Search launched in 2025: it widens the matching on a campaign and rewrites headlines and ad text. Performance Max spends one budget across Search, YouTube, Display and Maps and decides the split itself. Broad match paired with a smart bidding strategy is what Google recommends by default, and the recommendations tab will offer it again every week you decline.
Hand over the bidding once the conversion is right
Target CPA and maximize conversions both work in an HVAC account on one condition: the thing counted as a conversion is a job. A call from an ad that ran longer than a length you pick. A form that reached dispatch. A booked job imported back into the account from ServiceTitan, Housecall Pro or FieldEdge as an offline conversion, with the ticket value on it.
Count a page view or a 5-second call as a conversion and the bidding learns to buy page views and 5-second calls. It gets good at it quickly. The cost per conversion in the report falls all summer while the install calendar stays empty.
Keep the account structure by hand
Repair, replacement and maintenance run as separate campaigns with their own budgets. An $89 diagnostic and a $14,000 replacement should never share a daily budget, because in July the repair keywords eat it by noon and the replacement ads never serve. Locations drawn to the service area, with the suburbs the trucks skip excluded by name. Ad schedules that follow the weather and the hours somebody is answering the phone. One landing page per campaign, written for that job, which is why the landing pages are part of the ad build.
Keep the negative keywords by hand, every week
Left alone, broad match will buy jobs, salary, apprenticeship, training, DIY, parts, wiring diagram, how to, free, and every commercial or new-construction search if you serve neither. It will buy the town two counties over that shares a name with the one you cover. Someone reads the search terms report every Monday and adds what showed up.
This list is never finished. A shop that stopped adding negatives in September needs a different list by June, because the searches change with the season and each new match type widens the net again.
Where AI Max and Performance Max fit
Performance Max with brand exclusions can carry replacement retargeting: the homeowner who read the replacement page in the last 30 days, followed across YouTube and Display for a few weeks. It has no place on emergency repair, where the ad has to be at the top of a search page within a minute and you need to see what it bought.
AI Max is worth testing on the replacement campaign, where a wider net turns up phrasings nobody thought to add. Turn it on for that one campaign, leave the repair campaign alone, and read the search terms report both weeks.
Part of what broad match buys stays hidden
Google cut search term visibility in 2020, and a share of the terms a campaign matched never appears in the report. Nobody outside Google knows how large that share is in a given account. Two things make it survivable. The separate campaigns bound the leak to one daily budget. The booked job as the conversion judges the campaign on the work it produced, which is the reason to build cost per booked job before handing anything to automated bidding. Read the search terms report anyway, every week, for the part of it you can still see.