Maintenance agreements vary enormously in what they actually deliver. Two contracts at similar price points can mean a technician who changes filters and leaves, or one who takes readings, writes them down, and tells you which of your eleven rooftop units is going to be a problem next summer.

The difference is documentation. Here is what we think a visit should cover.

Mechanical, every visit

  • Filters — changed, and the size and quantity recorded so nobody guesses next time
  • Belts — tension and wear, with condition noted rather than just "OK"
  • Evaporator and condenser coils — inspected and cleaned; a dirty condenser is the most common cause of "it just is not cooling like it used to"
  • Condensate pan, drain, and trap — flushed and flowing, because a blocked drain is how a mechanical problem becomes a ceiling problem
  • Bearings and motors — noise, play, and amp draw
  • Economizer — dampers actually stroking, linkage intact, and the control responding

The readings that make a report useful

This is the part that separates a real report from a checkbox sheet. Every visit, on every unit, and written down so it can be compared to last time:

  • Supply and return air temperatures, and the temperature split
  • Refrigerant pressures with superheat and subcooling
  • Compressor and fan motor amp draw against nameplate
  • Static pressure where it can be measured
  • Electrical connections checked and torqued, with capacitors tested rather than eyeballed

One set of readings tells you whether a unit is operating correctly today. Three visits of readings tell you what is degrading, which is the whole point. A compressor drawing four percent more current every quarter is a story. The same reading with nothing to compare it to is just a number.

The test of a maintenance agreement: ask to see a sample report. If it is a page of ticks with no numbers on it, you are buying filter changes. If it has readings, photos, and a dated deficiency list with rough costs, you are buying information you can budget against.

What should come back to you afterwards

A visit should produce a short written record: what was done, the readings, photos of anything notable, and a deficiency list separated into fix now, plan for this year, and watch it. With rough numbers attached.

That last part is what makes capital planning possible. Most facility budgets get blown by failures nobody saw coming — not because the warning signs were absent, but because nobody wrote them down where a finance conversation could find them.

How often is enough

It depends on the equipment and the environment, not on a package tier. A restaurant with heavy grease loading and three rooftops needs a different frequency than an office suite with two. A plant with process cooling needs different attention again. Somebody should walk your equipment before proposing a schedule — if a frequency gets quoted over the phone without seeing the site, it was chosen for the contract, not for the building.

The honest case for it

Maintenance does not eliminate failures. What it does is move most of them out of the emergency column and into the planned column, and give you a repair list with numbers on it before the fiscal year starts. On multi-site portfolios that second benefit is usually worth more than the first.