HVAC Maintenance Guide
What a real tune-up includes, how often, and the readings worth keeping.
11 min
HVAC maintenance checklist
Two visits a year, twelve tasks each, and a dashed box beside every task that should leave a number behind. Print it blank and hand it to whoever does the work.
Tick as you go, or print it blank and fill it in on the truck.
- size / MERV
- in. w.c.
- °F ΔT
- °F SH / SC
- A / RLA
- µF
Notes and findings
- 01
- 02
What separates a tune-up from a cleaning
Numbers. A visit that produces no recorded readings has told you nothing about the system and cannot be compared to last year's visit. The dashed boxes in the list are the measurements worth paying for: static pressure, temperature split or rise, superheat and subcooling, amp draws against nameplate, capacitor microfarads, manifold gas pressure and carbon monoxide.
Keep the sheets. Three years of static pressure readings on the same system will show a filter slot slowly strangling the blower long before anyone notices the house is warm.
Reading the readings
| Reading | Expected | If it is off |
|---|---|---|
| Total external static | At or under the blower rating | Restriction: filter, coil, undersized return |
| Cooling temperature split | 16–22 °F at design conditions | Low: airflow or charge. High: airflow starved |
| Superheat / subcooling | Per the metering device | Charge, or a restriction upstream of it |
| Compressor amps | Below nameplate RLA | High: overcharge, dirty condenser, failing bearing |
| Capacitor | Within ±6% of rating | Weak start, hard start, eventual compressor damage |
| Furnace temperature rise | Inside the plate's range | High: airflow. Low: overfired or oversized blower |
| Manifold gas pressure | As stamped on the rating plate | Overfired or underfired; never adjust by ear |
| Carbon monoxide | Ambient near zero | Stop. Combustion or venting fault |
Safety items that are not optional
Safety — Combustion and refrigerant
The heat-exchanger inspection, the flue draft check and the CO reading are the three items on the fall list that exist to keep people alive. A cracked exchanger or a blocked flue is a red-tag condition, not a note for next year.
On the cooling side, section 608 of the Clean Air Act (40 CFR part 82, subpart F) bans intentional venting of ODS refrigerants and their substitutes, including HFCs, during service, repair or disposal. Gauges belong on a certified technician's manifold.
The filter is the whole first line
Both lists start with the filter because it is the item that changes most between visits and the one most often wrong. Record the size and the rating every time — EPA's guidance is at least MERV 13, or as high as the fan and slot can take. The size chart and the MERV chart settle both halves of that.
Sources: US EPA, Stationary Refrigeration and Air Conditioning (read 2026-09-04) · US EPA, Indoor Air Quality — What is a MERV rating? (read 2026-09-04)
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