It’s frustrating to wake up to a cold house. Before you call for a service technician, there are several troubleshooting steps you can take yourself. Many furnace issues are caused by simple, external factors rather than mechanical failure. If you need help we are only a call away.
Follow this step-by-step guide to diagnose why your heat isn’t kicking on.
Heat Troubleshooting
No Heat? Try These Tips
Heat Not Kicking On?
Check The Following:
1. Power: Reset the Furnace Breaker
Even if your lights are on, your furnace’s dedicated circuit may have tripped. Locate your electrical panel and look for the switch labeled “Furnace” or “Air Handler.” Flip it completely to the OFF position and then back to ON.
Pro Tip: Check the service switch (it looks like a light switch) located on or near the side of the furnace itself to ensure it hasn’t been accidentally toggled off.
2. Gas Supply: Confirm It’s On
If you have a gas furnace, ensure the fuel is actually reaching the unit. Check the gas shut-off valve on the pipe leading to the furnace; the handle should be parallel to the pipe. If it is perpendicular (forming a “T” shape), the gas is cut off.
3. Diagnostic Light: Check for Error Codes
Most modern furnaces have a small clear window on the lower panel. Behind it, an LED light will blink in a specific sequence (e.g., two short blinks, one long).
Note the pattern: Write down the code.
Check the Legend: There is usually a sticker on the inside of the furnace door that explains what each code means. This info is gold for a technician if you end up needing a repair.
4. Igniter: Is It Glowing?
The igniter is what lights the gas. During a startup cycle, you should see a bright orange or red glow inside the burner assembly. If you hear the furnace trying to start but never see that glow, the igniter may be cracked or burnt out.
5. Flame Sensor: Check for Steady Current
The flame sensor is a small rod that sits in the path of the flame. Its job is to tell the furnace that a fire has successfully started. If it’s dirty (covered in carbon soot), it won’t “sense” the flame and will shut the system down for safety.
The Sign: The furnace lights for a few seconds and then immediately goes out.
6. Pressure Switch: The Safety Gatekeeper
The pressure switch ensures that your inducer motor (the small fan that clears out exhaust) is working and that your vent pipe isn’t clogged.
How it works: When the inducer motor starts, it creates a vacuum. This vacuum closes the pressure switch, allowing 24V of electricity to pass through to the next stage of ignition. If the switch stays open, the furnace won’t fire up to prevent carbon monoxide buildup.
7. Limit Switch: Is It Overheating?
The limit switch is a safety device that shuts the furnace down if the internal temperature gets too high. The most common cause for this is a dirty air filter. If air can’t move through the furnace, the heat builds up until the limit switch trips to prevent a fire.
8. Reassemble & Test
Once you’ve checked these components, make sure all furnace panels are securely fastened. Most furnaces have a “door switch” that prevents the unit from running if the panel is loose. Turn your thermostat to “Heat,” set it a few degrees above room temperature, and observe a full cycle.
Still Feeling the Chill?
If you’ve gone through these steps and your home is still cold, it’s time to call in the professionals. Some repairs require specialized tools and handling of high-voltage electricity or gas lines.
Give us a call today at 717-874-2030 or Contact Us and we’ll get your home back to a comfortable temperature in no time!
Trust the Pros at Metropolitan HVAC
At Metropolitan HVAC, we’ve been serving homeowners and businesses across Camp Hill and Southcentral PA with dependable, expert heating services. When your boiler leaks, you don’t just need a patch—you need peace of mind. Our team is trained to identify the root cause of the problem, recommend the most cost-effective repair, and restore your system quickly and safely.
We offer:
- Fast scheduling and honest diagnostics
- Fair, upfront pricing on all boiler repairs
- 24/7 emergency support for no-heat situations
- Repairs on all major boiler brands and systems