A technician was at your house for twenty minutes. He looked at the outdoor unit, said everything seemed fine, and left. Was that an inspection?

Maybe. Maybe not. A real AC inspection covers about twenty checks across five parts of your system. Some are visual. Several need instruments and a reading compared against spec. We have inspected air conditioning systems in Houston homes since 2003, and the gap between a thorough visit and a quick look is wide.

Below is the full checklist, area by area. Use it to know what you are buying before you book, or to judge the visit you already had. You will also find the difference between an inspection and a tune-up, and what you should be handed when the technician leaves.

A full inspection covers five areas of your system.

• Thermostat and controls — calibration, cycling, and wiring
• Indoor unit — evaporator coil, blower motor, filter, and condensate drain
• Outdoor unit — condenser coil, fan, compressor, and refrigerant pressures
• Electrical — capacitors, contactor, connections, and amperage draw
• Airflow and performance — temperature split, vent output, and visible ductwork

Some of those are visual checks. Others need gauges, a meter, and a reading compared against what the manufacturer says it should be. The industry maintenance standard spells out which tasks are which. A technician who never opens a case or attaches an instrument has not inspected your system.

Here is the simplest way to judge it. A real inspection ends with a written report of what was found and measured. Not a verbal all-clear on the way to the truck.

Most inspections start here, because everything downstream takes its orders from this one device.

Calibration. Your technician compares the thermostat reading against the actual room temperature. A thermostat off by a few degrees runs your system longer than it needs to.

Cycling. Does the system turn on and off at the temperatures you set? Short cycling and long runtimes both point to something worth checking.

Wiring. The low-voltage wiring between your thermostat and your equipment carries every signal. Loose or corroded connections cause problems that look like equipment failure.

Batteries and programming. Digital and smart thermostats get checked for battery level, correct programming, and proper pairing with the system.

Placement. This one gets missed often. A thermostat in direct sun, near a supply vent, or on an exterior wall reports the wrong number. Your whole house runs off that wrong number.

This is where Houston systems show their age first. Humidity and attic installations make the indoor unit our most common source of findings.

Here is what gets checked:

• Evaporator coil — dirt buildup, corrosion, and any sign of ice
• Blower motor and blower wheel — operation, noise, and debris on the wheel
• Air filter — condition, size, and whether it is seated correctly in the housing
• Condensate drain line — clogs, slow drainage, and biological growth inside the line
• Drain pan — standing water, rust, and cracks
• Secondary pan and float switch — on attic units, the backup that stops a ceiling leak
• Cabinet and insulation — gaps, damaged insulation, and air leaking where it should not
• Signs of past water damage — stains on the platform, the pan, or the surrounding attic decking

Two of those deserve extra attention here.

Our humidity means your coil pulls a lot of moisture out of the air. That water has to leave through the drain line. Warm, damp, dark lines grow things, and growth turns into a clog.

The float switch is your safety net. It shuts the system down when water backs up in the pan. On an attic unit, a working float switch is the difference between a service call and a new ceiling.

The outdoor unit sheds the heat your system pulls out of the house. When it cannot do that job, everything else struggles.

What gets checked:

• Condenser coil — dirt, grass clippings, cottonwood, and bent fins
• Clearance around the unit — shrubs, vines, and fencing crowding the airflow
• Fan motor and blade — operation, noise, wobble, and blade damage
• Compressor — startup behavior, sound, and current draw
• Refrigerant pressures — read on both the high and low side and compared against spec
• Leak inspection — at the line set, service valves, and connections
• Line insulation — missing or deteriorated insulation on the larger refrigerant line
• Level and pad — a unit sitting out of level over time strains the compressor
• Disconnect box and whip — condition, corrosion, and secure connections

The pressure readings are the part a homeowner cannot judge from the driveway. Numbers on both sides of the system tell a technician whether your charge is correct, whether you have a restriction, and whether something is leaking.

That last item matters more here than most places. Our storms and our humidity are hard on outdoor electrical connections. A corroded disconnect is a common find and a cheap fix.

This is the area most often skipped, and the one most tied to a system quitting without warning. Electrical parts rarely give notice. They work until they do not.

• Capacitors — tested for actual capacitance against their rated value, not just checked for bulging
• Contactor — pitting, burning, and whether it is pulling in cleanly
• Voltage at the equipment — confirmed against what the system needs
• Amperage draw at the motors — measured and compared to the rating on the nameplate
• Wiring, terminals, and connections — looseness, corrosion, and heat discoloration
• Safety controls and float switches — tested, not just looked at
• Breaker and disconnect — condition and correct sizing

Two of these are worth understanding.

A capacitor gives your motors the push they need to start. It weakens gradually before it fails. A tested capacitor reading below its rating is a part you replace on a Tuesday in April instead of a Saturday in August.

Amperage draw is the tell for a motor going bad. A blower or compressor pulling more current than its nameplate says is working harder than it should. That shows up on a meter long before it shows up in your house.