HVAC · Troubleshooting

Furnace or Heat Not Working

If you're dealing with furnace or heat not working, this guide walks through what the symptom usually means, the causes worth ruling out, the checks you can safely do yourself, and the point where it's time to bring in a technician. Roxly handles heating repair throughout the Charlotte metro area.

What this symptom usually means

a heating system that won't produce heat has usually lost its ignition source, its airflow, or the electrical signal that tells it to run. It's rarely a single guaranteed cause, which is why a proper diagnosis matters.

Likely causes

• A failed igniter or pilot assembly. Gas furnaces need a working igniter or pilot to light the burners at all.
• A tripped flame sensor or safety switch. Modern furnaces shut down automatically if they can't confirm a safe flame, which can look like the unit 'not working.'
• A dirty air filter. Severe airflow restriction can trip a high-limit safety switch that shuts the furnace down.
• A failed blower motor. The burners may light, but with no blower running, no warm air reaches the house.
• A thermostat or control-board fault. A wiring or control issue can prevent the call for heat from ever reaching the furnace.

Safe checks you can do first

These are safe for anyone — no tools, gas, refrigerant, or electrical work:

• Replace the air filter if it's dirty.
• Confirm the thermostat is set to Heat, above room temperature.
• Check the furnace's power switch and the breaker haven't been bumped off.
• For gas units, confirm the gas supply valve is open.

What not to attempt

• Don't repeatedly attempt to relight a gas pilot that won't stay lit.
• Don't bypass a safety switch that's shutting the system down — it's doing its job.

Repair, not replace

Roxly performs HVAC repair and maintenance on already-installed systems. Most of the causes above are serviceable components — a capacitor, contactor, motor, or coil repair — not a reason to replace the whole system. We don't install new systems or replace a condensing unit, air handler, or furnace.

When to call a technician

If the basics check out and there's still no heat, the igniter, flame sensor, blower motor, or control board need a technician's diagnosis. A technician diagnoses the actual fault and reviews findings and an estimate before any work. Service availability may vary by location, equipment type, brand, technician availability, licensing requirements, and the scope of the requested work. Contact Roxly Appliance & Refrigeration Repair to confirm service availability for your address and equipment.

Frequently asked questions