The furnace runs, but the house won’t warm up
In Calumet City, a lot of calls sound like this. The furnace comes on, blows warm for a few minutes, shuts off, and the house never reaches the number on the thermostat. By evening you’re wearing a sweatshirt indoors. That pattern usually means the furnace is overheating and shutting itself down to stay safe.
Calumet City sits against Hammond on the Illinois side of the state line, and we cross over from Munster to cover it all the time. A real person answers day or night.
Calumet City homes
Much of Calumet City is older brick bungalows and modest mid-century homes, most with the furnace in the basement. Many have been through a few furnaces on the same ductwork. Add a finished basement, a closed-off register or two, and a filter that’s been in since fall, and airflow gets tight. Tight airflow is one of the most common reasons a furnace overheats. Some basements have been finished around the furnace with a door on the utility room. That room needs a louver or a gap under the door, because many furnaces pull their burner air from the space around them.
What the limit switch is telling you
Every gas furnace has a high-limit switch. If the air inside the furnace gets too hot, the switch shuts off the burners. The blower keeps running to cool things down, then the furnace tries again. That on-off-on cycle is the switch doing its job. The real question is why the furnace is getting that hot.
Often it’s a clogged filter. Sometimes it’s a blower that’s slowing down, blocked registers, or a worn limit switch that trips too early. We check airflow, test the switch and look at the blower before we name the repair. There’s more in why a furnace keeps turning on and off.
Things to check first
- Pull the filter and hold it up to a light. If you can’t see through it, replace it.
- Open the supply registers in every room, including the ones behind furniture.
- Make sure the return grilles aren’t blocked by boxes or rugs.
- Give it an hour. If the furnace is still cycling on and off, call us.
Use the size printed on the edge of the old filter. One that’s too thick or the wrong type for your furnace can choke airflow the same way a dirty one does.
When it’s the blower, not the filter
If the filter is clean, the registers are open, and the furnace still cycles off hot, the blower is next on our list. A blower that’s losing speed moves a little less air every week, and the furnace runs hotter to make up for it. We test the motor and its capacitor with a meter. A capacitor is a small part. A motor costs more. You see which one it is, and the price, before we do anything.
The written price
Once we know what’s wrong, the tech writes down a flat-rate price for the repair. You agree to it before we start, and the bill matches. Sometimes the whole fix is a new filter and a limit switch. Sometimes it’s more. Either way, you know the number first.
We don’t sell furnaces on repair calls
Our techs are not on commission. If the furnace is sound, we fix it. If we find something serious, like a cracked heat exchanger, we show you what we saw and give you the repair and replacement prices together so you can decide. A furnace’s age by itself doesn’t settle anything.
Safety across the line
If you smell gas, leave the house and call 911 or your gas company from outside. In Calumet City that’s your Illinois gas utility, so keep its emergency number handy. A furnace shutting off on its limit switch isn’t dangerous by itself, but one that trips over and over is a warning worth acting on. If a carbon monoxide alarm goes off, get everyone out and call 911.
Heat acting up in Calumet City? Call (219) 555-0142. We also cover Hammond and Lansing next door. See our furnace repair page for how every visit works, or the service area page for the full list of towns.
