Snellville HVAC: Fix Your Heating System Fast

Estimated Read Time: 10 minutes

Heater not working when Atlanta mornings turn cold? Here are the five most common causes and the safe fixes you can try before calling for service. If you still need help, Moncrief Heating & Air Conditioning offers same‑day service for plan members and quick scheduling across Atlanta, Roswell, Alpharetta, and Marietta. Keep reading for step‑by‑step checks, when to call a pro, and how to prevent the problem from coming back. Active coupons below can save you on today’s visit.

1) Thermostat or Power Issues

A surprising number of “heater not working” calls trace back to settings or power. Start here before opening panels.

What to check first:

1. Mode and setpoint
2. • Make sure Heat is selected and the set temperature is above the current room temperature.
   • If you have a programmable or Wi‑Fi thermostat, confirm the schedule is not holding a setback.
2. Power
3. • Replace thermostat batteries.
   • Check the furnace switch near the unit. It should be on.
   • Verify the breaker and any outdoor disconnects on heat pumps.
3. Smart thermostat resets
4. • If your app shows the device offline, reboot the router and thermostat, then reconnect.

When to call a pro:

• The thermostat keeps dropping offline.
• No power at the control board or repeated tripped breakers.
• Heat pump does not energize in Heat mode.

Safety note: If a breaker trips again after reset, stop and schedule service. That can indicate a short or motor failure.

"They came out immediately, within hours after I called, and spent an hour diagnosing the issue ... replaced our old smart thermostat with a new smart thermostat, and all has been well ever since!"

2) Dirty Filters and Airflow Restrictions

Restricted airflow makes your system overheat and shut down or makes rooms feel cold. It is one of the easiest DIY fixes.

How to restore airflow:

1. Change or clean the filter
2. • Replace 1‑inch filters every 1 to 3 months during heating season.
   • High‑MERV filters load faster. Check monthly.
2. Open vents and returns
3. • Keep at least 10 inches clear in front of returns.
   • Avoid closing too many supply registers. It raises static pressure and can trigger safety limits.
3. Clear the outdoor unit (heat pumps)
4. • Maintain 18 inches of clearance around the cabinet for proper airflow.

Why it matters:

• Furnaces have limit switches that shut burners off if the heat exchanger gets too hot.
• Heat pumps need steady airflow across indoor and outdoor coils to move heat efficiently.

Moncrief’s Total Comfort Service Plan includes filter checks and professional cleaning to keep airflow in the safe zone. Plan members get same‑day service when they request before noon, which is invaluable during a cold snap.

"We are thrilled with the performance, astounded by how quiet they are compared to the old systems, and we love the technological leap of the new thermostats and the accompanying app."

3) Ignition, Flame Sensor, or Pilot Problems (Furnaces)

If the blower runs but the air is cold, the burners may not light or stay lit. Common culprits include a faulty ignitor, dirty flame sensor, or pilot issues on older units.

DIY checks you can do safely:

1. Listen and observe
2. • Do you hear a click, then a short attempt to light, followed by a shutdown? That points to ignition or flame sensing.
2. Cycle power
3. • Turn the furnace switch off for 60 seconds, then back on to reset the control board.
3. Replace the filter
4. • Overheating from low airflow can trip the limit and stop ignition.

Professional repairs we perform:

• Ignitor or flame sensor replacement.
• Gas pressure and manifold adjustments per manufacturer specs.
• Combustion analysis and vent safety checks.

Why Moncrief for gas systems:

• Our heating maintenance checklist includes: check gas burners, pilot and tubing, flame baffle, manifold pressure, gas input, burner air adjustment, thermocouple, gas valve, pilot safety, combustion chamber, ignition, filters, fan and limit control, thermostat, vent system, and operation. These are the exact steps that prevent nuisance lockouts.

"He found the problem, a faulty ignitor, and quickly repaired our heating system. He also cleaned and checked both of our furnaces and corrected a few other minor problems."

4) Heat Pump Not Heating: Defrost, Reversing Valve, or Thermostat Logic

A heat pump that blows cool air in Heat mode often has a control issue or is stuck mid‑defrost. In Atlanta’s damp winters, outdoor coils frost up, and systems must defrost correctly to maintain comfort.

Quick checks:

1. Mode and balance point
2. • Confirm Heat mode. If you have dual fuel, the thermostat should bring on the furnace when outdoor temps drop below the set balance point.
2. Outdoor unit status
3. • If the fan is stopped and steam rises briefly, the unit may be in a normal defrost cycle. Give it a few minutes.
3. Airflow and filter
4. • Dirty filters or iced coils reduce capacity and can feel like cooling.

Common professional fixes:

• Reversing valve or defrost control board replacement.
• Outdoor sensor calibration.
• Refrigerant charge check and leak testing.

Why pro setup matters:

• Correct thermostat configuration and staging keep your home warm without excessive energy use. As a Trane Authorized dealer, Moncrief configures advanced controls and verifies performance in real conditions across Roswell, Alpharetta, Smyrna, and beyond.

"The installation went smoothly and they showed us how to work the new thermostat before they left. We are very satisfied with their work and the new system."

5) End‑of‑Life Equipment or Sizing Mismatch

If your system is 12 to 20 years old, frequent lockouts, rising utility bills, and uneven rooms can point to a unit at the end of its life or one that was never sized correctly.

Signs it is time to evaluate replacement:

1. Repeated major repairs in the last two years.
2. Safety concerns like cracked heat exchangers.
3. Comfort complaints in key rooms even after duct and control fixes.

What Moncrief does differently:

• Proper design: We perform full heat‑loss calculations and equipment matching with our engineering partner. This ensures the right capacity and airflow for your home, not just a like‑for‑like swap.
• System options: High‑efficiency furnaces, variable‑speed heat pumps, ductless mini‑splits for additions or third‑floor spaces, and even residential boilers. Moncrief is one of the few companies in Atlanta that still installs and services residential boilers.
• Better ownership experience: New installs include a free one‑year maintenance agreement. Our plan provides scheduled visits, and for members, same‑day service with free parts and labor on covered repairs.

"Next day the installation team came over and replaced both units and did a spectacular job, were so pleasant and polite! I couldn't be happier."

Prevent It: A Simple Seasonal Checklist

Follow this quick plan each fall so you are not caught with a heater not working when cold hits Sandy Springs or Marietta.

1. Replace filter and clear returns.
2. Test Heat mode for 10 minutes. Confirm warm supply temperature.
3. Check the outdoor heat pump for clearance and debris.
4. Vacuum around the furnace, not inside the burner compartment.
5. Schedule professional maintenance before peak season.

What our technician will do on a heating tune‑up:

• Verify gas pressure, burner flame, and ignition sequence.
• Inspect venting and heat exchanger safety.
• Test thermostat, fan and limit controls.
• Measure temperature rise and static pressure.
• Clean sensors and critical components.

Two grounded facts you can count on:

• Moncrief has served greater Atlanta for over 125 years.
• We are a Trane Authorized dealer and maintain ongoing technical training for our team, including support for NATE certifications.

If you still find your heater not working after these steps, schedule service. We cover Atlanta, Lawrenceville, Roswell, Alpharetta, Marietta, Smyrna, Snellville, Norcross, Acworth, and Ellenwood with fast response.

Special Offers for Heating Service

• Save 40% on Heating Maintenance. Regular in‑season pricing now through Oct 31.
• $50 OFF Heating or Cooling Service or Repair for NEW Customers.
• $50 OFF our Total Comfort Service Plan. New plan participants only. Cannot be combined with other offers.

Call (404) 350-2300 or book at https://moncriefair.com/. Mention the offer when scheduling to lock in your savings.

Frequently Asked Questions

How often should I service my heater in Atlanta?

Twice per year. We recommend an AC tune‑up before heat rises in spring and heating maintenance when temperatures begin to fall. This timing catches issues early and keeps warranties and efficiency on track.

My furnace clicks but does not light. What should I do?

Replace the filter, verify the furnace switch is on, and try a power cycle. If it still fails, you likely have an ignitor or flame‑sensor issue. Stop and schedule service to avoid repeated lockouts or gas safety risks.

Why does my heat pump blow cool air in winter?

During defrost, the outdoor unit reverses and can feel like cool air briefly. If it never warms up, you may have a control, sensor, or refrigerant issue. Have a pro check defrost controls and charge.

Is it worth repairing a 15‑year‑old furnace?

If the heat exchanger is sound and repairs are minor, yes. If you face repeated major repairs or rising bills, a right‑sized, high‑efficiency replacement often pays back through lower energy and fewer breakdowns.

Do you service boilers in Atlanta homes?

Yes. We are one of the few Atlanta contractors that still install and service residential boilers. We also handle radiators, controls, and annual safety checks.

Final Takeaway

If your heater not working is derailing your day, start with thermostat, power, and filter checks. When ignition, defrost, or sizing issues are in play, call a pro. Moncrief’s 125‑year Atlanta track record, Trane Authorized expertise, and full‑home design approach mean fixes that last.

Ready to Get Warm Again?

Call (404) 350-2300 or schedule at https://moncriefair.com/. Use $50 OFF Heating or Cooling Service for NEW Customers or save 40% on Heating Maintenance through Oct 31. Plan members get same‑day service with free parts and labor on covered repairs. We serve Atlanta and nearby cities daily.

Call now: (404) 350-2300 • Book online: https://moncriefair.com/ • Save today: $50 OFF Heating Service for NEW Customers or 40% OFF Heating Maintenance through Oct 31.

About Moncrief Heating & Air Conditioning

For over 125 years, Moncrief has kept Atlanta comfortable with expert heating, cooling, and plumbing. We are a Trane Authorized dealer with licensed, insured, and background‑checked technicians. Homeowners choose us for custom system design, whole‑home performance, and our Total Comfort Service Plan that includes twice‑yearly maintenance and same‑day service for members. We’re one of the few Atlanta companies that still install and service residential boilers. Expect clear communication, a text with your tech’s photo and live ETA, and work done right the first time.