Lennox HVAC Repair

Need help with your Lennox heating and cooling system? This guide covers common problems and solutions for Lennox HVAC equipment.

Many issues can be fixed without calling a service tech if you understand the basics.

About Lennox Systems

Lennox makes many types of heating and cooling equipment. Air conditioners, heat pumps, gas furnaces, oil furnaces, air handlers, and packaged units all carry the Lennox name. Each system has its own quirks, but they share many parts.

Find your model number before doing anything else. Look for a data plate on the unit with model and serial information. Write this down.

Older systems like the HS29 heat pumps often have compressor problems as they age. Newer models like the XC25 air conditioners sometimes have control board issues. The SLP98V furnaces occasionally have communication problems between components.

Systems made before 2010 use different refrigerant than newer ones. This affects what repairs make sense. Older systems might need more extensive work because some parts aren't made anymore.

Air Conditioner and Heat Pump Issues

Cooling problems show up in several ways. These affect both air conditioners and heat pumps.

• No cooling often means the system runs but doesn't cool your home. Check the thermostat first. Make sure it's set to "cool" and below room temperature. Set the fan to "auto" not "on" for proper cooling.

• Outside unit won't run? Check the disconnect switch near the outdoor unit. Make sure circuit breakers haven't tripped. Bad capacitors or failed compressors prevent outdoor units from running.

• Poor cooling happens when the system runs but doesn't cool well. Low refrigerant, dirty filters, or dirty coils cause this. Refrigerant issues need professional service.

• Short cycling means the system turns on and off too quickly. This wears out parts faster. Oversized equipment, refrigerant problems, dirty filters, or bad thermostats cause this.

• Ice on refrigerant lines or indoor coils means airflow problems or refrigerant issues. Turn off the system until ice melts, then check filters and make sure all supply registers are open.

Merit series units sometimes have fan motor problems after a few years. You might see the outdoor unit running but the fan not turning. Fix this quickly to prevent compressor damage.

Strange noises from outdoor units mean trouble. Different sounds point to different problems. Grinding usually means bearings failing. Rattling suggests loose parts. Hissing might be refrigerant leaks.

Heating System Problems

Lennox heating systems have their own set of issues. These affect furnaces and heat pumps in heating mode.

• No heat often means the thermostat settings are wrong, power is off, or gas supply is interrupted. Check that the thermostat is set to "heat" and above room temperature.

• Not enough heat happens when the system runs but doesn't warm adequately. Failing blower motors, improper gas pressure, dirty filters, or duct problems cause this. Airflow restrictions are most common and easiest to fix.

• System starts but shuts down before heating means a safety switch has activated. Dirty filters, flame sensor issues, or venting problems trigger safety shutdowns. Elite series furnaces really need proper venting.

• Burning smells when heat first comes on each season are normal briefly. Dust burning off the heat exchanger causes this smell, which should go away soon. Constant burning smells need immediate attention.

• Pilot lights going out on older systems might mean thermocouple problems, drafts, or gas supply issues. Newer Lennox models use electronic ignition instead of standing pilots.

• Blower runs without stopping usually means control problems, limit switch issues, or wrong thermostat settings. Check the fan setting on your thermostat first - it should be "auto" not "on" for normal running.

• Uneven heating throughout your home suggests airflow problems or duct issues. Some rooms being colder than others happens often with forced-air systems.

Install carbon monoxide detectors with any gas heating system. Replace batteries yearly. Any carbon monoxide concerns need immediate professional HVAC repair service.

Thermostat and Control Issues

Many problems start at the thermostat. These affect both heating and cooling.

• System won't turn on at all? Check thermostat power first. Replace batteries in battery models. Check breakers for hardwired ones. Communicating systems need power at both the thermostat and equipment.

• Wrong temperature readings make systems run at the wrong times. Check thermostat location. Keep it away from sunlight, lamps, TVs and other heat sources. Don't put it on outside walls or near drafts.

• Programming problems happen with digital models. iComfort thermostats sometimes lose settings after power outages. They might need reprogramming or new batteries.

• Wi-Fi connection problems affect smart thermostats. They need good Wi-Fi signals to work right. Weak signals cause remote features to work intermittently.

• Wiring can work loose over time. This causes erratic operation. Turn off power before checking or tightening connections to prevent control board damage.

• Wrong settings cause many problems. Check your manual for the right settings. Communicating systems need specific setup steps.

• Old thermostats might not work with newer equipment. If you replaced your HVAC system but kept the old thermostat, it might not be compatible. Newer Lennox systems work best with their matching thermostats.

Airflow Problems

Airflow affects both heating and cooling performance.

• Dirty filters restrict airflow. This makes everything work harder. Change filters regularly - every 1-3 months depending on your home. Pets and dust mean more frequent changes.

• Blocked vents reduce system performance. Keep furniture, rugs, and curtains away from vents. Keep all vents open, even in unused rooms. Closing too many creates pressure problems.

• Leaky ducts waste energy and reduce comfort. Look for disconnected ducts in attics, crawlspaces, or basements. Professional testing finds hidden leaks.

• Small ducts can't move enough air. Older homes retrofitted with air conditioning often have this problem. Signs include weak airflow, short cycling, and rooms far from equipment being uncomfortable.

• Dirty blower wheels reduce airflow. They get dusty over time and need cleaning. Signs include reduced airflow even with clean filters.

• Zone system problems create temperature imbalances. If you have motorized zone dampers, they can fail. Some areas get too hot or cold while others feel fine.

• Duct insulation breaks down over time. Poorly insulated ducts in unconditioned spaces waste energy. Look for damaged insulation in accessible areas.

Electrical Parts and Wiring

Electrical problems cause many HVAC failures.

• Capacitors help motors start and run. When they fail, motors struggle or don't run. Bad capacitors often look swollen. They need careful handling when replaced.

• Contactors control power to outdoor units. They develop pitted contacts over time. Listen for chattering sounds from outdoor units or compressors not running when they should.

• Transformers convert voltage for control systems. When they fail, thermostats and controls stop working. Check voltage output if you suspect transformer problems.

• Circuit boards run all modern systems. They fail from age, power surges, or moisture. Look for burned spots or corrosion on boards.

• Loose wiring causes intermittent problems. Years of vibration works connections loose. Check connections occasionally.

Signature series equipment uses special communicating controls. The communication path between components must stay intact.

Surge protection prevents electrical damage. Power fluctuations harm electronics in modern systems. Consider whole-house surge protection in areas with unstable power.

Refrigerant System Problems

Refrigerant issues need professional help. EPA rules require certification to handle refrigerant. Call us for AC repair if you suspect these problems.

• Low refrigerant causes poor cooling and eventually damages compressors. Look for ice on refrigerant lines, long running times, and weak cooling. This means a leak needs fixing before adding refrigerant.

• Leaking coils lose refrigerant over time. Indoor and outdoor coils develop small leaks at joints or from corrosion. Finding and fixing leaks needs special equipment.

• Compressor problems include electrical failures, mechanical wear, and flow issues. Unusual outdoor unit noises often mean compressor trouble. Hard starting, tripped breakers, or no cooling with the fan running suggests compressor issues.

• Refrigerant restrictions block proper flow. Dirt, moisture, or oil problems in the refrigerant circuit cause this. Parts of the coil get much colder than others or cooling performance suffers.

• TXV valves control refrigerant flow based on temperature. They can stick or fail. This causes inconsistent cooling and unusual temperature differences.

• R-22 refrigerant systems face repair challenges. This refrigerant is phased out and expensive when available. Consider replacement rather than major repairs on R-22 systems.

• Systems made after 2010 use R-410A refrigerant. This runs at higher pressure and needs compatible parts. Never mix refrigerant types.

System Maintenance

Regular HVAC maintenance prevents many problems and makes systems last longer.

• Change air filters often. This simple task prevents serious problems. Check monthly and change when dirty.

• Keep outdoor units clear. Leaves, grass, and shrubs block airflow through condensers. Keep at least two feet of clearance around all sides.

• Clean condensate drains yearly. They carry moisture away and can clog with algae. Flush with vinegar to prevent clogs.

• Get professional heating and cooling system maintenance yearly. Spring for cooling systems and fall for heating systems work best. Pros clean hard-to-reach parts and catch developing problems early.

• heck thermostat operation before each season. Replace batteries yearly. Program the right settings for the coming season.

• Listen for new noises when systems start running each season. New sounds almost always mean problems starting. Early fixes prevent expensive repairs.

• Keep vents and returns clear. Good airflow keeps systems healthy and efficient. Don't block air movement with furniture.

• Watch utility bills for sudden increases. Rising energy costs without more usage often mean efficiency problems developing.

Getting Replacement Parts

Need parts for your Lennox system? Sears Parts Direct has genuine replacement components. Use your model number to get the right parts.

Some parts look alike but have different specs. Match electrical ratings and part numbers exactly, not just appearance.

Control boards must match your model precisely. Even slight variations cause compatibility problems.

Keep old parts until the repair works well. Sometimes you need to compare them with new parts or return defective ones.

Some older Lennox parts have updated designs. New versions work fine but might look different.

When to Get Help

Some HVAC repairs need professional appliance repair service:

• Refrigerant work requires EPA certification and special equipment. This includes leak repairs and refrigerant charging.

• Electrical issues beyond simple problems need special testing equipment and training.

• Heat exchanger problems need professional inspection. Cracked heat exchangers create serious safety risks.

• Compressor replacements need specialized tools and skills. These major repairs require proper evacuation and charging.

• Control problems in communicating systems often need factory-specific diagnostic tools. Signature and Elite series use special communication systems.

If your Lennox system needs repairs you're not comfortable making, give us a call. Our service team knows these systems well and can fix them right the first time.