Why this one works
Most direct mail asks someone to want something they were not thinking about. A pre-season maintenance reminder does the opposite: it arrives just before the moment the customer was going to need you anyway.
That timing advantage is the whole mechanism. A homeowner who has not thought about their air conditioner since last August is not resistant to servicing it — they simply have not been prompted. The card is the prompt.
It also arrives before the rush rather than during it, which is better for you. Work booked in April is work you can schedule. The same customer calling in July is an emergency call you may not be able to take.
When to send
Four to six weeks ahead of the season turning is the window. Early enough that the customer has not had the uncomfortable week yet, late enough that the weather feels relevant.
In most of the country that means a cooling drop landing in April and a heating drop landing in September. Adjust to your own climate rather than the calendar — if your first hot week is reliably in May, mail in early April.
Allow for delivery. First Class mail takes a few days, and a staggered send takes longer still. Work backward from the date you want cards in hands, not the date you want to press send.
Who should get it
Start with customers whose last service is more than a year old. They know you, they have your equipment history, and the message can be specific in a way it cannot be for a stranger.
Sort your service records by last visit and pull everyone past twelve months. In most HVAC businesses that list is larger than the owner expects, because service customers churn quietly — they do not cancel, they just stop calling.
If you have equipment install dates, a second list is worth building: systems old enough to be approaching replacement. That is a different card with a different offer, and it is worth far more per response.
What to put on it
Name the season and the specific service. "Get your A/C checked before the first hot week" tells the reader what and when in one line.
A specific price beats a percentage. "$89 pre-season tune-up" is easier to say yes to than "15% off maintenance", because the reader does not have to do arithmetic to know what they are agreeing to.
Include a deadline that lines up with your schedule filling. And put a QR code on it — for a service business where most bookings happen by phone, a scan is often the only way to know the card was the reason the phone rang.
What it costs to run
A 4×6 card costs $1.19 all-in on CardCadence, including printing, First Class postage, and mailing. Six hundred lapsed service customers is $714.
Against a tune-up ticket that is a modest return per job, but maintenance customers are not bought for the tune-up. They are bought because a serviced system produces the repair call, and eventually the replacement quote, and those are the jobs that matter.
Calculate against that, not against the $89. If a maintenance customer eventually produces a system replacement, the acquisition math on a $1.19 card is not close.