Few situations are more frustrating for homeowners than hearing the comforting hum of a furnace fan only to realize that no heat is coming out. If you’ve ever searched for terms like furnace fan runs but no heat, furnace fan works but no heat, furnace blower working but no heat, furnace fan on but no heat, or furnace fan turns on but no heat, you know exactly what I’m talking about.
The good news is that in most cases, this is not a sign of catastrophic failure. In this article, I’ll break down why this happens, using the Goodman MBVK electric furnace as our example. We’ll cover common causes, troubleshooting steps, safety considerations, and preventative maintenance, giving you a complete understanding of what’s happening when your furnace fan is running but the heat isn’t.
Understanding the Goodman MBVK Electric Furnace
The Goodman MBVK is a modern, electric, variable-speed air handler that uses electric heating elements to warm your home. Unlike gas furnaces, it doesn’t rely on combustion, so many of the issues that cause “no heat” in gas furnaces, such as pilot light failure or gas valve problems, don’t apply.
Key features of the MBVK include:
-
Variable-speed ECM blower for consistent airflow
-
Modular electric heat kits
-
Integrated safety controls
-
Compatibility with various duct configurations, including upflow and downflow
Understanding how the MBVK operates helps explain why you might hear the blower running while heat is absent.
Common Reasons Your Furnace Fan Runs But No Heat
There are several reasons why your Goodman MBVK or other electric furnaces may have a running fan but no heat. Let’s break down the most common causes.
1. Thermostat or Control Setting Issues
Sometimes the problem is as simple as the thermostat. If the thermostat is set to “Fan On” rather than “Heat,” the blower will run continuously without activating the heating elements.
Check for:
-
Thermostat mode: Make sure it’s set to “Heat”
-
Set temperature: Ensure it’s higher than the current room temperature
-
Thermostat wiring: Loose or damaged wires can prevent the call for heat from reaching the furnace
Even with a properly functioning furnace, if the control signal isn’t sent, the heating elements won’t energize. You can read more about thermostat troubleshooting at HVAC.com.
2. Tripped Breaker or Blown Fuses
Electric furnaces rely on high-voltage circuits to power the heating elements. If a breaker trips or a fuse blows, the fan may still operate if it runs on a separate low-voltage or auxiliary circuit, while the heating elements remain off.
Check for:
-
Circuit breakers in the main panel
-
Fuses specific to the heating element circuit
-
Signs of overheating or burned connections
Resetting the breaker or replacing a fuse often resolves this issue. However, repeated trips indicate an underlying problem that needs attention.
3. Blown Heating Elements
In an electric furnace, heating elements are similar to oversized toaster coils. Over time, elements can burn out due to age, high load, or poor airflow.
Signs include:
-
Fan runs, but no heat output
-
Visible damage if the furnace is inspected carefully (disconnect power first!)
-
Uneven heating or partial heating when multiple stages exist
Replacing a heating element usually restores full function. MBVK elements are modular, making replacement straightforward when you follow safety procedures. Detailed replacement guides are available through manufacturers such as Goodman.
4. Tripped High-Limit Switch
Electric furnaces include safety limits to prevent overheating. If airflow is restricted — due to dirty filters, blocked ducts, or closed vents — the high-limit switch may trip, cutting power to the elements while keeping the blower running.
What to check:
-
Clean or replace air filters
-
Open supply and return vents
-
Ensure ductwork is clear and free of obstructions
Once the furnace cools down, most high-limit switches reset automatically. Persistent tripping requires professional inspection to prevent damage.
5. Blower Running Without Heat for Circulation
Some systems are designed to circulate air even without heat. If your furnace has recently run, residual heat may be sufficient for the thermostat to maintain fan operation without activating the heating elements. This is normal behavior in some variable-speed electric systems like the MBVK.
6. Control Board or Sequencer Issues
The MBVK uses a control board to manage heating stages. If the board detects a fault or fails, it may allow the blower to operate while disabling the heating elements to protect the system.
Symptoms of a board issue include:
-
Fan runs, but no heat
-
Furnace cycles intermittently
-
Error codes displayed on diagnostic LEDs
Control board faults are less common but can occur due to power surges, wiring issues, or component failure. Reference the MBVK manual for diagnostic LED codes.
Safety First: What Not to Do
When troubleshooting furnace fan runs but no heat, it’s important to prioritize safety:
-
Always turn off power before inspecting the furnace
-
Never bypass limit switches or other safety devices
-
Avoid touching heating elements or wiring directly
-
Call a licensed technician if you are unsure about electrical components
High-voltage circuits in electric furnaces can be lethal if mishandled. For more safety guidance, Energy.gov provides resources on home electric heating safety.
Step-by-Step Troubleshooting Approach
Here’s a structured approach to diagnose the issue:
-
Check thermostat settings: Ensure the system is in “Heat” mode and temperature is set above current room temperature.
-
Inspect breakers and fuses: Reset or replace as necessary.
-
Examine airflow: Replace filters and clear vents.
-
Observe the furnace: Note any unusual sounds or error codes.
-
Check heating elements: Only if you’re qualified; otherwise, call a technician.
-
Monitor high-limit switches: Determine if overheating caused a trip.
-
Evaluate the control board: Inspect for visible damage or LED error codes.
Following this process helps identify the root cause without unnecessary guesswork.
Preventing Future “Fan Runs but No Heat” Scenarios
Prevention is often easier than repair. Key preventative steps include:
-
Regular filter replacement every 1–3 months
-
Annual professional inspection of the furnace
-
Ensuring ductwork is unobstructed and properly sized
-
Checking electrical connections periodically
-
Monitoring system performance and noting unusual sounds or smells
Maintaining your MBVK electric furnace according to manufacturer guidelines maximizes lifespan and minimizes downtime. Resources like HVAC.com provide seasonal maintenance checklists for electric furnaces.
When to Call a Professional
While some minor issues (like replacing filters or resetting breakers) can be handled by homeowners, you should contact a licensed HVAC technician if:
-
Heating elements are suspected to be burned out
-
The high-limit switch trips repeatedly
-
The control board shows error codes
-
Fan runs but no heat persists after basic checks
-
There are signs of electrical damage
Professional technicians can safely inspect, test, and repair high-voltage components, ensuring long-term reliability.
Why the Goodman MBVK Is Reliable
Despite occasional “fan runs but no heat” issues, the Goodman MBVK is a robust and reliable electric furnace. Its strengths include:
-
Variable-speed blower for efficient airflow
-
Modular heat kits for easy maintenance
-
Integrated safety features that protect both the home and the equipment
-
Compatibility with a range of duct configurations, including upflow and downflow
-
Ease of diagnostic troubleshooting for HVAC professionals
Proper installation, routine maintenance, and quick response to minor issues keep the MBVK running efficiently for many years.
Final Thoughts from Jake Lawson
If your furnace fan runs but no heat, it’s important to remember that the system is usually protecting itself rather than failing catastrophically. Common causes range from thermostat settings and tripped breakers to airflow issues, high-limit switches, or burned-out heating elements.
The Goodman MBVK electric furnace combines modern safety features with reliable heating performance, making it a straightforward system to troubleshoot once you understand its operating principles. By following structured troubleshooting steps, maintaining proper airflow, and observing safety precautions, most issues can be resolved efficiently — and preventatively.
Understanding the underlying logic behind furnace fan works but no heat, furnace blower working but no heat, or furnace fan on but no heat puts homeowners and technicians in a better position to keep their homes warm safely and reliably.
