Furnace Not Working? A Safe No-Heat Checklist for Iowa Homes

No heat and safety Updated 2026-10-22 · By Kasey, Waukee, Iowa · 7 sources

It is the first truly cold night of the year in Waukee, the thermostat says 64 and falling, and you can't hear the furnace kick on. Before you panic, there are a handful of safe, no-tools checks you can do yourself. Just as important, there are a few situations where you should stop checking and get out of the house.

This guide draws on the CDC, the EPA, ENERGY STAR, the U.S. Department of Energy, and the safety pages of MidAmerican Energy and Alliant Energy. It never asks you to open the furnace, relight anything or touch gas piping. Those are jobs for a licensed heating technician.

Step 0: Gas smell or CO alarm? Get out first

If you smell gas. MidAmerican Energy says natural gas has no odor on its own, so it adds an odorant that smells like rotting eggs or a skunk. A leak can also make a quiet hiss or a loud roar. MidAmerican's instruction is to leave the area immediately, then call its gas-leak line at 800-595-5325 and call 911 from a safe distance. Alliant Energy's page gives the same "move fast" advice: evacuate everyone, go to a remote location and call 1-800-ALLIANT (800-255-4268), and call 911 if gas lines or equipment are broken and gas is blowing. Alliant adds: don't stop to look for the leak or open windows, and don't use anything that might make a spark, such as a cell phone, light switch or garage door opener, until you're away from the building.

If your gas comes from a municipal utility or another provider, use the emergency number on your bill or that utility's website.

If a CO alarm sounds. MidAmerican says to leave your home immediately and get fresh air, call 911 if anyone feels sick, and have a qualified technician, such as a home heating technician or plumber, find the source before you go back to normal.

The CDC describes carbon monoxide as an odorless, colorless gas that can cause sudden illness and death. Gas- and oil-burning furnaces are among the household sources it names. The CDC lists the most common symptoms as headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion, often described as "flu-like." People who are asleep can die from CO before they notice symptoms. The EPA adds that symptoms which clear up after you leave home are a warning sign. It lists leaking chimneys and furnaces, back-drafting furnaces, and blocked, disconnected or leaking flues among the sources of CO indoors.

Step 1: Check the thermostat

If nobody smells gas and no alarm is sounding, start with the easy part. These are ordinary owner checks, not repairs:

• Is it set to "Heat"? After a fall of running the AC, it's easy to leave a thermostat on "Cool" or "Off."
• Is the set temperature above the room temperature? Raise it a few degrees and wait several minutes.
• Does the screen work? A blank display on a battery-powered thermostat often just means dead batteries. Your thermostat's manual will say how to change them.

Step 2: Check the furnace filter

A badly clogged filter can choke off the airflow a furnace needs. ENERGY STAR tells homeowners to inspect, clean or change air filters once a month in a furnace, central air conditioner or heat pump. It says a dirty filter can raise energy costs and damage equipment, leading to early failure. The Department of Energy's consumer guide likewise says to clean or replace filters monthly during peak seasons.

If the filter is caked, replace it with the size printed on its frame. Your owner's manual or contractor can show you how.

Step 3: Check power to the furnace

A furnace needs electricity even when it burns gas. Without opening any panels:

• Look at your home's electrical panel for a tripped breaker labeled furnace or HVAC. If it trips again right after you reset it, stop and call a professional. That's a sign of a fault, not something to keep resetting.
• Many furnaces have a service switch near the unit that looks like an ordinary light switch. Make sure it hasn't been flipped off by mistake.

Step 4: Check outdoor vents after snow

This one is very Iowa. Alliant Energy warns that snow and ice can block exhaust vents for gas appliances, especially after a big storm. Vents on the roof or the side of a house must stay clear to vent properly, which prevents carbon monoxide build-up and equipment malfunction. If your furnace vents through pipes on a side wall and they're buried in a drift, Alliant says to clear snow carefully with your hands or a broom, not by kicking or shoveling, which could cause damage. Alliant also says not to plant shrubs in front of furnace exhaust pipes, because blocking them can cause CO to build up. If you need help, call a professional.

Never climb onto a snowy roof to clear a vent. Call a pro instead.

Step 5: Know when to stop and call a pro

If the thermostat, filter, power and vents all check out and you still have no heat, the problem is inside the furnace. Think ignition, flame sensing, the blower motor, controls or gas pressure. That is technician work. ENERGY STAR's maintenance checklist lists checking gas connections, gas pressure, burner combustion and the heat exchanger among the heating tasks a contractor should do. It warns that faulty gas connections are a fire hazard and that a dirty burner or a cracked heat exchanger can make equipment run less safely.

Things not to do while you wait:

• Don't keep resetting the furnace or a breaker that keeps tripping.
• Don't open the burner compartment or try to relight anything.
• Don't heat your home with a gas oven. The CDC says never do this.
• Don't run a generator indoors or in the garage, even with the door open. The CDC says to keep generators outside, more than 20 feet from windows, doors and vents.

Wondering whether it's time to replace an older furnace instead of repairing it? See our furnace replacement guide. For hiring, see how to choose an HVAC company in Iowa.

Prevent the next no-heat night

The best fix is the one you never need. All of these come straight from the sources above:

• Book a yearly heating check-up in the fall. The CDC says to have your heating system, water heater and other fuel-burning appliances serviced by a qualified technician every year. ENERGY STAR recommends heating check-ups in the fall, before contractors get busy, and suggests tying them to the clock change. The DOE guide says furnaces should be checked in the fall.
• Have CO alarms where you sleep. The CDC recommends battery-operated or battery back-up CO detectors near every sleeping area. Check their batteries when you change the clocks each spring and fall, and replace the detector per the manufacturer's instructions or every five years. MidAmerican recommends at least one CO detector on every level of the home.
• Have your chimney checked or cleaned every year, per the CDC, since debris can cause CO to build up indoors.
• Change filters monthly in heating season.

Frequently asked questions

Why is my furnace blowing cold air?

Start with the safe checks above: thermostat mode and setting, the filter, and snow-blocked vents. If it still blows cold, call a heating technician rather than opening the furnace.

Should I call 911 if my CO alarm goes off?

MidAmerican Energy says to leave the home immediately and get fresh air, and to call 911 if you or a family member feel sick. Then have a qualified technician find the source of the CO before using the appliance again.

What does a gas leak smell like?

MidAmerican and Alliant both add an odorant to natural gas so leaks smell like rotten eggs (MidAmerican also says a skunk smell). If you smell it, leave first, then call your gas utility and 911 from a safe distance.

How often should a furnace be serviced?

The CDC recommends having your heating system serviced by a qualified technician every year, and ENERGY STAR recommends doing heating check-ups in the fall.

How often should I change my furnace filter?

ENERGY STAR says to inspect, clean or change filters once a month in your furnace, air conditioner or heat pump, and the Department of Energy says monthly during seasons of peak use.