Gas odor or hissing
Leave immediately. Don't touch switches, thermostats, appliances, phones, or garage controls inside or near the suspected leak. Call 911 and the gas utility from outside.
Frederick HVAC FAQ
What should I check before calling for no heat?
Start with the thermostat, heating-system power, filter, and open supply and return vents. These safe observations can catch a changed setting or restricted airflow without turning a small question into a risky furnace repair.
If heat doesn't come back, leave internal controls, burners, wiring, and safety devices alone. Write down what the system did, then call us.
Safety comes first
Some no-heat symptoms are not a troubleshooting project.
Carbon monoxide alarm
Move everyone to fresh air, call 911 or the fire department, and stay out until responders say it's safe to go back in. Carbon monoxide has no color or odor.
Smoke, sparks, or a loud ignition boom
Leave damaged electrical parts and combustion equipment alone. Turn the system off only if you can do so without entering an unsafe area or touching the damage.
See Washington Gas natural gas safety and the CPSC carbon monoxide guidance for emergency response steps.
Only when the home is safe
Keep the check short and in order.
Start with safety, then thermostat, power, and airflow. Give the system a few minutes to respond after a correction. One intentional power check is enough.
- 01
Set the thermostat to call for heat.
Set the mode to Heat, raise the setpoint several degrees above the room temperature, and use Auto for the fan test. A blank display may mean lost power or dead homeowner-accessible batteries. Don't remove wires or change installer settings.
- 02
Check the system switch and breaker once.
A furnace switch can look like an ordinary light switch near the equipment. Check that it's On, then look for a labeled furnace, boiler, air-handler, or heat-pump breaker. If it trips again, leave it off and call us.
- 03
Open the air path.
Turn the system off before removing an accessible filter. Replace a visibly loaded filter with the correct size, and open supply registers and larger return grilles. From a safe position, look for snow, ice, leaves, or debris blocking outdoor heat-pump or vent openings.
- 04
Watch what happens next.
After a setting or battery change, give it 2 to 3 minutes for a normal control delay. Note whether the system's silent, clicks, starts the blower, attempts ignition, runs briefly, or blows cool air. That sequence tells us more than any guess at a failed part.
- 05
Leave internal controls alone.
Don't remove panels, bypass a rollout or limit switch, reset a safety device, test live wiring, or work on burners, gas valves, venting, or combustion parts. Photograph a visible fault code without opening the equipment.
Stop at the cabinet door.A filter, vent, thermostat, or accessible switch is a homeowner check. Burners, gas valves, combustion air, venting, heat exchangers, and internal electrical parts are ours to diagnose.
For basic filter and furnace checks, see Carrier's furnace no-start guidance and ENERGY STAR's HVAC maintenance checklist.
Useful information
Tell us what changed, not what part you guessed.
Note when the heat stopped, what the thermostat showed, whether the blower ran, whether you heard ignition, and whether the filter or breaker changed anything. A blower running with no warm air points us in a different direction than a completely silent system does.
For a Frederick County home, call us for no-heat diagnosis when the safe checks don't restore heat. Call sooner for repeated shutdowns, breaker trips, water near electrical equipment, heavy heat-pump ice, abnormal ignition sounds, or a rapidly falling indoor temperature.
While you wait
Stay warm without creating another hazard.
If you use an electric space heater, plug it directly into a wall outlet on a stable, level surface with at least three feet of clearance from bedding, curtains, paper, furniture, children, and pets. Don't use an extension cord or power strip, and don't leave it running while everyone sleeps.
Never heat the home with a gas oven, range, charcoal grill, or outdoor fuel-burning heater. Close doors to unused rooms, use safe layers and blankets, and move people to a warmer location if the temperature keeps falling.
Read the CPSC winter heating safety noticeFast answers
Questions homeowners ask next.
A clear observation helps the service call. A repeated reset or an opened safety control doesn't help us at all.
Should I reset my furnace breaker?
Check it once if there's no smoke, water, or electrical odor. If it trips again, leave it off and call us. Repeated resets can keep energizing a failed component and wipe out fault information we'd otherwise see.
What if the furnace clicks but does not start?
Record the clicking and whether the blower runs, then stop there. Don't keep cycling the thermostat or bypass ignition and safety controls.
Can I relight an older standing pilot?
Follow only the relighting steps printed on the appliance or in its manual, and only when there's no gas odor and you can identify every control. If the pilot won't light or stay lit, stop and call us.
When is no heat an emergency?
Gas odor, a carbon monoxide alarm, smoke, electrical burning, unsafe indoor temperatures, repeated shutdowns, or conditions that threaten pipes or vulnerable occupants all need urgent safety attention, fast.
A short safe check is enough
Share what the thermostat, blower, filter, switch, and breaker did without opening the furnace.