Vent, Valve & VoltHVAC checklist
Leave or call right now
- You smell gas or rotten eggs, or hear hissing or blowing near a gas line or the meter.Leave the building now and take everyone with you. Don't flip switches, use appliances or use a phone inside. Call 911 or your gas utility once you're well away from the house.
- A carbon monoxide alarm is going off.Get everyone outside, then call 911. Don't go back in until responders say it's safe.
- People in the house have headaches, dizziness, weakness, nausea, chest pain or confusion, especially when the heat is running.Get everyone outside to fresh air, then call 911.
- A burning, metallic or chemical smell from the furnace, or soot around the furnace or its vents.Shut off the furnace, ventilate the house, and call an HVAC technician. If a CO alarm sounds or anyone feels sick, get outside and call 911.
- A burning or musty smell when the AC runs.Set the thermostat to Off and call an HVAC technician.
- The furnace vent pipe outside is blocked by snow, leaves or a nest.Turn the furnace off and call an HVAC technician. If a CO alarm sounds, get outside and call 911.
Safe to try first
- Replace the air filter. Trane and Carrier recommend every 1 to 3 months; Bryant suggests checking it monthly and replacing it every 30 to 90 days.
- Check the thermostat settings: Cool or Heat as needed, fan on Auto, and for cooling, at least 3 to 5 degrees below room temperature, as Lennox suggests.
- Replace thermostat batteries with fresh alkaline batteries of the same brand, as Honeywell recommends. Trane suggests doing it yearly.
- Open closed supply vents, clear furniture and rugs off vents and return grilles, and keep interior doors open, as Energy.gov advises.
- With the power off at the disconnect, clear leaves, grass and snow from around the outdoor unit and keep plants about 2 feet away, per Trane.
- Clear a clogged condensate drain with a wet/dry vac at the outdoor end and diluted vinegar at the indoor access point, as Lennox and Carrier describe. Turn the AC off first.
- Thaw a frozen AC by switching from Cool to Off and running the fan on On. Carrier and Lennox both suggest it. Never chip at the ice.
- Reset a tripped breaker once, opening only the hinged panel door, never the metal cover behind it. If it trips again, leave it off and call a technician.
Call a pro soon
- Hissing, oily residue near the AC or heat pump lines, or ice that keeps coming back after you change the filter and open the vents.A licensed HVAC technician with EPA Section 608 certification.
- The outdoor unit hums or clicks but the fan won't spin, or stays silent with the power on.A licensed HVAC technician.
- The furnace clicks over and over but never lights, or lights and goes right out.A licensed HVAC technician.
- A breaker for the AC, furnace or heat pump trips again after one reset.A licensed HVAC technician.
- The furnace keeps short cycling with a clean filter and open vents, or you see rust or corrosion on it.A licensed HVAC technician. Turn the heat off until they've checked it.
- The condensate drain keeps clogging, the drain pan is cracked or rusted through, or there's water damage.A licensed HVAC technician.
- Your fuel-burning furnace or boiler hasn't been inspected in the last year.A licensed HVAC technician, for a routine inspection.
Write this down before you call
What kind of system do you have?
What does the heat run on?
What's happening?
When did it start, and did anything change around then?
Thermostat brand and model, and is the screen on?
When was the air filter last changed?
Any blinking light on the furnace or air handler?
What is the outdoor unit doing when the system should be running?
Ice or water anywhere?
Any smells or sounds?
Did a breaker trip?
Equipment brand, model, serial and age
Every stop-and-call sign and try-first step comes from the sources listed at ventvalveandvolt.com/vent/when-to-call-an-hvac-pro/.