Tips & Resources

10 Common Causes for Furnace Service Calls and How to Avoid Them

10 Common Causes for Furnace Service Calls and How to Avoid ThemEach year when it starts getting colder, we get a lot of calls from Coloradoans who tried to turn on their heating system only to discover that there’s some kind of problem.

The vast majority of service visits in the Denver Metro Area resulting from these calls involve the same 10 issues. We’ve outlined them below, along with 5 things you can do to reduce the incidence of these problems.

What are common causes for service calls?

Most calls we get as the Colorado winters grow closer involve one or more of the following concerns.

1. Continuously-Running Blower

Blower issues can indicate a problem with the limit switch. This usually requires the intervention of a professional service technician.

2. Dirty Air Filters

Dirty or clogged air filters impede airflow, forcing the furnace to work harder. Clogged filters can also damage the limit switch.

3. Electric Ignition or Pilot Control

Thermocouple problems, drafts, and clogs can result in a faulty ignition or unlit pilot.

4. Faulty Thermostat

A malfunctioning thermostat can lead to problems with comfort levels or a fan that doesn’t turn properly.

5. Failure to Heat

Problems with the thermostat setting, gas, pilot light, or power can cause an inability for the furnace to do its primary task.

6. Insufficient Heat

A clogged filter can cause a furnace to produce insufficient heat. Another cause is a unit that’s too small for the space it’s attempting to heat. Our service technician will check your unit and make recommendations as appropriate.

7. Frequent Cycling

Cycling between the “On” and “Off” modes may indicate a clogged filter, improper airflow, or incorrect thermostat setting.

8. Lack of Maintenance

Some homeowners occasionally skip annual furnace inspections and maintenance calls. Whether that’s on purpose or not, doing so can lead to unexpected problems. Routine system tune-ups help prevent breakdowns and keep your system running efficiently.

9. Noisy Furnace

Squeaking, rumbling, or rattling sounds are not standard and typically indicate a mechanical problem, clogged burner, or reduction in airflow.

10. Wear and Tear

Normal wear and tear of a system over time can cause problems with heat control (including overheating) and airflow.

What can I do to reduce the frequency of these problems?


Make it a habit to schedule a routine maintenance checkup on your furnace at the end of each summer or right after Labor Day. A professional tune-up will prepare your system for the upcoming cold season and address problems that can cause more expensive repairs or breakdowns. Enroll in our Preventive Maintenance Program and we’ll automatically schedule regular maintenance visits for this purpose.

Change Air Filters

Many furnace problems are the result of dirty or clogged air filters. Clean or replace your filters monthly while the system is in daily use or every 2-3 months when the system is being used only intermittently.

Check Circuit Breaker and Power Supply

If your thermostat screen goes blank or the furnace stops working, check to see if you’ve tripped a circuit breaker or blown a fuse. Also, make sure that power cords are plugged in.

Check Thermostat

Check the thermostat battery level if your furnace is not producing heat as expected. Sometimes this problem can be fixed simply by replacing the battery.

Reduce drafts

If your pilot light keeps going out, you may need only to close a window or door in the room to avoid drafts. If that doesn’t work, give us a call for a check-up.

Rely on Colorado Discount Heating & Cooling

If nothing seems to work, call us to schedule a service call. We’ll check out your system thoroughly, detail the repairs needed, or explain why you may need a system replacement.

Homeowners and businesses in Englewood, CO, and the Denver Metro Area, rely on Colorado Discount Heating & Cooling. Our certified technicians, flat-rate pricing, honest advice, and superior customer service can’t be beaten.

Contact us today to consult with our team and get customized HVAC solutions from our trained and experienced professionals.

Why Choose Us?

  • 100% Satisfaction Guarantee
  • Integrity Guarantee
  • Property Protection Guarantee
  • Labor Guarantee
  • Cleanliness Guarantee

Our Guarantees

We stand by the quality of our services, which is why we provide each customer with a 100% Satisfaction Guarantee. All services are billed at a flat rate corresponding to the project, rather than an hourly rate, to help our customers save money.

100% Satisfaction Guarantees

We Proudly Serve the Denver Metro Area

Find your service area & give our team a call. Colorado Discount Heating & Cooling is just a phone call away.

Request Service