Why Is My HVAC System Not Working? 7 Signs to Act On

Few things are more frustrating than coming home expecting comfort—only to be greeted by stuffy air or a completely unresponsive HVAC system. HVAC repair issues are common, especially during extreme weather when systems are under maximum stress. Whether it’s blowing warm air, short cycling, or not turning on at all, these problems never come at a convenient time.

Many homeowners overlook early warning signs until a total breakdown occurs. But identifying the root causes early on can prevent costly repairs or full system replacements. If your heating or cooling isn’t working as it should, it could be one of these seven common issues.

1. Clogged or Dirty Air Filters

Restricted airflow is one of the leading reasons an HVAC system stops working efficiently—especially in high-demand areas like Mobile AL or when using systems such as Netherland Air Conditioning. When filters are full of dust, dirt, or debris, air struggles to pass through the system.

Why it matters:

Poor airflow can cause overheating and system shutdowns.
It increases energy consumption and decreases indoor air quality.

Quick tip: Check and replace your filters every 30 to 90 days, especially during peak seasons.

2. Thermostat Malfunctions

Sometimes the issue lies with the thermostat rather than the HVAC unit itself. An incorrectly set, damaged, or outdated thermostat can lead to erratic operation or complete shutdown.

Look out for:

Blank screen or unresponsive buttons.
Incorrect temperature readings or delayed response.
System not responding to settings.

Smart thermostats may require software updates or recalibration, while older models may need replacement.

3. Low Refrigerant Levels

Refrigerant is essential for the cooling process. If your system is low on refrigerant due to a leak or improper charge, it won’t cool effectively—no matter how long it runs.

Warning signs:

AC blowing warm or room-temperature air.
Ice forming on coils or refrigerant lines.
Hissing or bubbling sounds near the unit.

Only licensed professionals can handle refrigerant safely. If you suspect a leak, schedule an HVAC inspection right away.

4. Tripped Circuit Breaker or Blown Fuse

Power-related issues are another common reason an HVAC system stops working. A tripped breaker, blown fuse, or disconnected wiring can shut down the entire unit.

What to check:

Your home’s electrical panel for any tripped breakers.
Outdoor unit disconnect switches.
Visible signs of burnt wires or smells.

Important: Always use caution with electrical components and call a technician if you're unsure.

5. Blocked Condenser Unit

The outdoor condenser unit plays a crucial role in heat exchange. If it’s covered by debris, leaves, or dirt, it can’t release heat effectively, which causes system overload or inefficient cooling.

Signs include:

Unit is running but not cooling.
System cycles on and off frequently.
High energy bills.

Keep the area around your unit clear and have the coils cleaned at least once a year.

6. Damaged Blower Motor

The blower motor pushes conditioned air through the vents. When it fails, even if your HVAC is technically running, you won’t feel much airflow.

Symptoms:

Weak airflow from vents.
Burning smell or buzzing sound.
Sudden system shutoff after starting.

Motor issues typically require replacement and should be handled by a certified HVAC professional.

7. Leaky or Unsealed Ductwork

You may have a perfectly functioning HVAC system, but if your ductwork has leaks, much of that cooled or heated air will never reach your living space.

How it affects you:

Uneven temperatures in different rooms.
Excess dust and poor air quality.
Higher utility bills despite normal usage.

Professional duct sealing and insulation can improve system efficiency by up to 30%, according to the U.S. Department of Energy.

Take Action Before It Gets Worse

If your HVAC system is showing signs of failure, don’t delay. Regular maintenance, such as filter changes, coil cleaning, and thermostat checks, can prevent most common problems. But for more technical issues—especially refrigerant or motor failures—it’s best to contact a licensed HVAC repair service. Prompt action ensures you stay comfortable, efficient, and safe all year round.

FAQs

Q1: How much does HVAC repair typically cost in 2025?

A: On average, basic HVAC repair costs range from $150 to $600. More complex issues like refrigerant leaks or blower motor replacements can run between $700 to $1,500, depending on the unit type and labor rates in your area.

Q2: How often should HVAC systems be serviced?

A: Experts recommend twice a year—once before the cooling season (spring) and once before the heating season (fall). This helps catch minor issues before they become major repairs.

Q3: Why is my HVAC blowing air but not heating or cooling?

A: This could be due to a faulty thermostat, dirty filters, low refrigerant, or even duct leaks. A system inspection is necessary to pinpoint the exact cause.

Q4: Can I do any HVAC repairs myself?

A: While you can change filters and clean around the unit, most HVAC repairs—especially electrical, refrigerant, and internal components—should be handled by licensed professionals for safety and warranty reasons.

Q5: How do I know if I need a repair or full HVAC replacement?

A: If your system is 10–15 years old, needs frequent repairs, or is inefficient despite regular maintenance, it may be more cost-effective to replace it. A professional can help assess the best option for your home and budget.