Decatur, GA Heating System Not Working? 5 Quick Fixes

Estimated Read Time: 12 minutes

Heater not working right when you need it most? You are not alone. Atlanta’s winter swings can stress older heaters and even new systems. This guide breaks down five common reasons your heater is not working and how to fix each one safely. Get quick DIY checks, signs you should call a pro, and ways to prevent repeat breakdowns. New customers can also save with our limited-time coupons below.

1) Thermostat or Power Issues

A surprising number of no-heat calls are caused by simple control or power problems. If your heater is not working, start here before opening panels or ordering parts.

Steps to try now:

1. Confirm the thermostat is set to Heat and the setpoint is above room temperature.
2. Replace batteries in older or non-hardwired thermostats.
3. Check the furnace or air handler switch. It looks like a light switch near the unit.
4. Inspect the breaker panel. Reset any tripped breakers by switching fully OFF, then ON.
5. For smart thermostats, verify Wi‑Fi and manufacturer app settings. Re-run equipment setup if recently changed.

When to call a pro:

• The display is blank after new batteries.
• Your heat pump or furnace runs but blows cool air.
• Wires were recently moved or a new thermostat was installed.

Prevention tips:

• Label the furnace switch so it is not turned off by mistake.
• Use a surge protector for sensitive equipment in storm-prone areas.
• Document thermostat settings season to season, especially if you switch between heat pump and auxiliary heat.

“They came out immediately, within hours after I called, and spent an hour diagnosing the issue before they determined our old thermostat had gone bad. They never rushed and thoroughly explained the problem.”

2) Dirty Filter or Blocked Airflow

Restricted airflow is a top cause of weak heat, short cycling, or heat pump freeze-ups. In metro Atlanta, pollen and construction dust clog filters faster than many homeowners expect.

What to check:

1. Locate the return filter at the grill or inside the air handler.
2. If the filter looks gray, fuzzy, or damaged, replace it. Match size and orientation.
3. Open supply registers fully. Avoid furniture, curtains, or rugs blocking vents.
4. For heat pumps, make sure the outdoor unit is clear of leaves and debris on all sides.

What you might notice:

• Furnace runs but rooms never warm up.
• Heat pump ices over on cold, damp days.
• Energy bills jump even though you did not change settings.

When to call a pro:

• Ice persists after clearing the coil and filter.
• You smell burning dust each cycle beyond the first few minutes of winter startup.
• The blower runs but there is almost no airflow from vents.

Prevention tips:

• Replace 1-inch filters every 30 to 60 days in heavy pollen months.
• Consider a media cabinet with a 4- to 5-inch filter for longer life and better airflow.
• Add a professional airflow check during fall tune-ups.

“New HVAC system installed today. Moncrief did a great job, showed up on time and got the work done efficiently. Cleaned up too. Looking forward to more efficient heating and cooling.”

3) Ignition or Flame Sensor Problems (Gas Furnace)

If your gas furnace clicks but will not stay lit, the ignitor or flame sensor may be the culprit. These parts wear with age, especially after long idle periods.

DIY checks you can do safely:

1. Turn off power to the furnace. Remove the front panel.
2. Look for a window on the burner compartment. If you see repeated tries to ignite followed by shutdown, suspect ignition control.
3. Do not sand the flame sensor. Light cleaning with a soft cloth may help, but a technician test is best.
4. Restore power and watch the sequence from a safe distance. If the flame starts then stops, do not keep cycling.

Signs you need service:

• Error codes flashing on the control board.
• Sulfur or sharp gas odor. Leave the home and call the gas utility before anything else.
• Frequent short cycling or loud booms at startup.

Why this happens:

• Worn hot surface ignitors crack over time.
• Flame sensors corrode in humid basements or closets.
• Poor grounding or a dirty burner can prevent flame recognition.

“A senior technician found the problem, a faulty ignitor, and quickly repaired our heating system. He also cleaned and checked both furnaces and corrected a few other minor problems.”

4) Heat Pump in Defrost or Refrigerant Trouble

On chilly, damp Georgia mornings, heat pumps can frost over. That is normal during defrost cycles, but the system should clear the ice within minutes. If it stays iced or delivers cool air, there may be a deeper issue.

What you can check:

1. Is the outdoor fan turning and free of ice buildup?
2. Do you hear a temporary whoosh and change in tone during defrost? That is normal.
3. Verify auxiliary heat stages are available on very cold nights.
4. Make sure the thermostat is set to Heat, not Emergency Heat, unless directed by a tech.

Red flags to call for help:

• Thick ice persists after 30 minutes.
• Repeated defrost cycles with no real heating.
• Hissing or bubbling sounds near the outdoor unit.
• High energy use with poor comfort.

What a pro will do:

• Check refrigerant charge and look for leaks.
• Test reversing valve performance and defrost controls.
• Confirm proper airflow across indoor and outdoor coils.
• Calibrate thermostat heat pump settings.

“We had a new variable-speed SEER 16 Bosch heat pump installed. The team matched our efficiency goals and set up the smart thermostat. All has been well ever since.”

5) Safety Switches, Drain Problems, or Blower Failures

Modern systems protect themselves by shutting down when they sense risk. If your heater starts, then quits, a safety device may be doing its job.

Common triggers:

1. Condensate drain clogs trip a float switch. High-efficiency furnaces and air handlers produce water that must drain.
2. Overheating due to dirt or a failed blower causes a high-limit switch trip.
3. Duct issues like collapsed flex or closed dampers starve the blower.

Homeowner steps:

• Check for water near the furnace or air handler. Clear the drain pan and call for service.
• Replace the filter and reopen closed vents.
• Listen for blower start. If silent or grinding, power down and schedule a repair.

What techs check:

• Motor amperage, capacitor health, and wheel cleanliness.
• Pressure switches, inducer performance, and venting.
• Drain line slope, traps, and cleanout access.

“Installation went smoothly and the team worked professionally in a very cramped space. We are thrilled with the quiet performance and the app-connected thermostat.”

When to Repair vs Replace

Age, repair frequency, and utility costs guide the decision.

Consider replacement when:

1. Gas furnace is 15 to 20 years old with a cracked heat exchanger risk or repeated ignitor failures.
2. Heat pump is 12 to 15 years old with a major refrigerant leak or compressor issues.
3. Repair costs exceed 30 percent of the price of a new, efficient system.
4. Comfort problems persist despite proper duct and airflow corrections.

Why replacement can pay off:

• New variable-speed furnaces and inverter heat pumps deliver steadier temperatures and quieter operation.
• Rebates and financing can offset upfront cost. Our team helps you find incentives for high-efficiency systems.
• Moncrief includes a complimentary one-year maintenance agreement on new installs, reducing ownership risk in year one.

Local insight:

• Atlanta’s damp cold makes heat pump defrost strategy and auxiliary heat sizing critical. Our engineer-led load calculations match equipment to your home so you stay warm without waste.

Pro Maintenance That Prevents No-Heat Emergencies

A tuned system runs safer and longer. Our Total Comfort Service Plan schedules heating and cooling visits automatically so you do not have to remember.

What our techs do at a heating tune-up:

1. Test safety controls, ignition, and gas pressure for furnaces.
2. Verify refrigerant charge, defrost, and reversing valve on heat pumps.
3. Clean burners or coils, check airflow, and calibrate the thermostat.
4. Inspect the blower, capacitors, and electrical connections.
5. Measure temperature rise and static pressure to catch duct issues early.

Plan perks you will feel:

• Twice-yearly maintenance with priority scheduling.
• Same-day repairs with parts and labor included if an issue arises, per plan terms.
• Lower utility bills, better air quality, and fewer surprise breakdowns.

Hard facts that matter:

• Moncrief has served Atlanta for 125+ years.
• Licenses: HVAC CN210646 and Plumbing MP209933.

DIY Fixes vs Professional Help: Safety First

Safe to try yourself:

1. Change filters and clear vent obstructions.
2. Check breakers, furnace switch, and thermostat batteries.
3. Gently clear debris around the outdoor heat pump unit.

Call a licensed pro for:

1. Gas leaks, ignition problems, or repeated error codes.
2. Refrigerant issues, defrost failures, or iced equipment.
3. Blower motor failures, grinding noises, or repeated limit trips.

Choosing the right partner:

• Look for licensed, insured technicians who can show training on your brand.
• Expect upfront pricing and a clear diagnostic before parts are replaced.
• Ask about warranty coverage and whether a one-year maintenance plan is included with a new system.

With Moncrief, you receive a text with your tech’s photo and live map on appointment day. Our team uses drop cloths and booties to protect your home while we work.

Special Offers

• Save 40% on regular season pricing for heating maintenance. Offer valid for non-plan customers only. Must mention offer when scheduling. Expires 2025-10-31.
• New customers save $50 on heating or cooling service or repair. Must be a new customer to redeem. Expires 2026-03-04.

Call 770-341-2178 or schedule at https://moncriefair.com/. Mention the offer you want when booking.

What Homeowners Are Saying

"Our furnace stopped heating in January during a cold spell. A senior technician found the problem, a faulty ignitor, and quickly repaired our heating system. He also cleaned and checked both furnaces and corrected a few other minor problems."

"Moncrief did a fantastic job replacing our two mid-2000s HVAC systems. 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 app to manage them."

"New HVAC system installed today. Moncrief did a great job, showed up on time and got the work done efficiently. Answered all questions. Cleaned up too. Can’t even tell they were here. Looking forward to much more efficient heating and cooling!"

Frequently Asked Questions

Why is my heater blowing cold air?

Thermostat settings, clogged filters, or a furnace safety trip can cause cool air. Confirm Heat mode, change the filter, and check breakers. If the burner lights then shuts off, call a pro to test ignition and safety controls.

How often should I replace my furnace filter in Atlanta?

During heavy pollen seasons, check monthly and replace every 30 to 60 days for 1-inch filters. Larger 4- to 5-inch media filters can last 3 to 6 months depending on dust, pets, and usage.

Is it normal for my heat pump to ice over?

Light frost is normal during defrost in cold, damp weather. Ice should clear within minutes. If thick ice remains after 30 minutes or performance drops, schedule service to check charge and defrost controls.

When should I repair instead of replace my heater?

Consider repair if the unit is under 10 years old and the fix is minor. Replace if repairs exceed 30 percent of a new system cost, or if you face frequent failures and high bills despite tune-ups.

Do you service boilers as well as furnaces and heat pumps?

Yes. Moncrief is one of the few Atlanta providers that still installs and services residential boilers, in addition to furnaces, ductless systems, and heat pumps.

In Summary

If your heater is not working, start with thermostat and power checks, then filters and airflow. For ignition, defrost, or safety trips, a licensed pro is your safest path. In Atlanta, Moncrief fixes the root cause and helps prevent repeat failures with expert maintenance.

Ready to Get Warm Again?

Call 770-341-2178 or book at https://moncriefair.com/ for same-day heating repair. New customers save $50 on service through 2026-03-04, or get 40% off a heating tune-up if you are not on a plan. Mention your preferred coupon when you call.

Call now: 770-341-2178 • Book online: https://moncriefair.com/ • New customer coupon: $50 off heating or cooling repair through 2026-03-04. Save 40% on heating maintenance for non-plan customers through 2025-10-31.

About Moncrief Heating & Air Conditioning

For over 125 years, Moncrief has kept greater Atlanta comfortable with engineered system design, expert installs, and same-day service. We are a Trane Authorized dealer with licensed, insured, background-checked technicians. All new installs include equipment warranties and a complimentary one-year service plan. Licenses: HVAC CN210646, Plumbing MP209933. Expect upfront pricing, technician ETA text with photo, and booties to protect your home. Choose Moncrief for boilers, furnaces, heat pumps, ductless, IAQ, and custom HVAC.