HVAC maintenance - and how to spot a fake tune-up

What is hvac maintenance?

HVAC maintenance is a scheduled service visit - usually annual, or twice a year if you have separate heating and cooling equipment - in which a technician cleans, inspects, measures and adjusts the system. A proper visit takes roughly 60 to 90 minutes and ends with written readings. Anything much shorter than that, with no numbers at the end, was not a tune-up.

Signs you need hvac maintenance

• The system has not been serviced in more than a year, or you have never had it serviced
• You have just bought the house and have no service history for the equipment
• The manufacturer warranty requires documented annual maintenance to stay valid
• Running costs have crept up without any change in the weather or your thermostat habits
• The system is getting louder, or the outdoor coil is visibly furred with dirt and cottonwood
• Airflow from the registers is weaker than it used to be
• A high-efficiency furnace or a heat pump that has never had its condensate system checked

Seeing something not on this list? Browse hvac problems by symptom →

How hvac maintenance actually works

1. 1

   Airflow and filtration

   The filter is checked and replaced or cleaned, the blower wheel is inspected for the dirt build-up that quietly strangles airflow, and static pressure is measured across the air handler. Static pressure is the single most informative number in the visit.

   Watch forA visit where the filter change was the whole job. Swapping a filter is a five-minute task you can do yourself. If nothing else was measured, you have paid a technician to do your errand.

2. 2

   Coils, drains and the wet side

   The outdoor condenser coil is cleaned of grass, cottonwood and dirt; the indoor evaporator coil is inspected; the condensate pan and drain line are cleared and the float switch tested. A blocked condensate drain is one of the most common causes of a mid-summer shutdown, and one of the easiest to prevent.

   Watch forNo hose, no coil cleaner and no wet condenser. Cleaning an outdoor coil is a visibly messy job. If the unit looks exactly as it did before the technician arrived, it was not cleaned.

3. 3

   Electrical and mechanical checks

   Capacitor capacitance is measured against its rated value, contactor points are inspected for pitting, amp draw on the compressor and motors is checked against nameplate, and connections are tightened. This is how a failing capacitor gets caught in April rather than in July.

   Watch forA capacitor "tested" by eye. It has a printed rating and a meter reading; a weak one measures below spec long before it fails. That measurement is a large part of what preventive maintenance actually buys you.

4. 4

   Combustion or refrigerant performance

   On a furnace: burner inspection, flame sensor cleaning, draft check and a combustion analysis for carbon monoxide. On cooling equipment: superheat and subcooling measured to verify the refrigerant charge, and temperature split across the coil.

   Watch forOn combustion equipment, no combustion analyser. On cooling equipment, gauges connected as a matter of routine - repeatedly connecting and disconnecting gauges can itself lose refrigerant, so a good technician uses temperature readings first and only gauges when something looks wrong.

5. 5

   Report, readings and honest recommendations

   You should receive a written record: static pressure, capacitor readings, amp draws, temperature split or rise, combustion figures, and any parts flagged as ageing. That document is your baseline for next year and your evidence for a warranty claim.

   Watch forA verbal "everything looks good" with no paperwork, or its opposite - a long list of urgent-sounding add-ons presented on the spot. Real findings come with numbers attached. Discretionary upsells rarely do.

What does hvac maintenance cost?

A single maintenance visit typically runs $100 to $250, and an annual plan covering two visits with a discount on repairs generally sits in the low hundreds per year. Very cheap advertised tune-ups are usually priced as a route to a sales conversation.

See the full hvac maintenance cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →