Fix Heat Pump: Complete Troubleshooting Guide (2026)

When your heat pump acts up, it can throw your whole home into disarray. The simplest way to fix a heat pump is to start with the basics: check the thermostat settings, inspect the air filter, reset the circuit breakers, and clear the outdoor unit. Many common problems boil down to these simple maintenance tasks or setting adjustments. The good news is that you can often troubleshoot and even fix a heat pump yourself with a little guidance.

This guide will walk you through everything from the easy first checks to diagnosing more complex problems, helping you understand when it’s possible to fix a heat pump yourself and when it’s time to call a professional.

Start Here: The Easiest Heat Pump Troubleshooting Steps

Before you panic, always start with the basics. These simple steps resolve a surprising number of problems and are often the easiest way to fix a heat pump, saving you the cost of a service call. If you get stuck, browse quick fixes from other homeowners and techs in our General Discussion forum.

Check Your Thermostat

The thermostat is your heat pump’s brain. If it’s not set correctly, the system won’t work as expected.

• Mode Setting: Make sure it’s set to “Heat” in the winter and “Cool” in the summer. It sounds obvious, but it’s a frequent mistake.

• Temperature Setting: Ensure the target temperature is actually calling for heat or cooling (e.g., set higher than the room temperature for heat, lower for cooling).

• Fan Setting: Set the fan to “Auto,” not “On.” If the fan is set to “On,” the blower will run continuously, even when the heat pump isn’t actively heating or cooling the air, which can make the air feel cold.

• Power: Check if the thermostat display is on. If it’s blank, it may need new batteries or there could be a power issue.

Inspect the Air Filter

A dirty air filter is a leading reason people need to fix heat pump problems. It restricts airflow, forcing the system to work harder and less efficiently.

• Reduced Airflow: A clogged filter can prevent enough air from passing over the coils, leading to poor heating or cooling.

• System Overheating: Lack of airflow can cause your heat pump to overheat and shut itself down as a safety measure.

• Frozen Coils: In cooling mode, a dirty filter can cause the indoor evaporator coil to freeze into a block of ice.

It’s recommended to check your filter monthly and replace it every 30 to 90 days. If you can’t see light through it, it’s time for a change.

Look for Tripped Breakers

Your heat pump has both an indoor and an outdoor unit, and they often have separate circuit breakers in your home’s electrical panel.

• Check the Panel: Find the breakers labeled for your “Air Handler,” “Furnace,” or “Heat Pump.”

• Reset if Needed: If a breaker is tripped, flip it fully to the “Off” position and then back “On.”

• Repeated Tripping: If the breaker trips again immediately, there’s likely a more serious electrical issue. Do not keep resetting it. This is a sign you need to call a professional to fix your heat pump.

Clear Your Outdoor Unit

The outdoor unit needs to “breathe” to transfer heat effectively.

• Debris: Remove any leaves, grass clippings, twigs, or dirt that have accumulated on or inside the unit.

• Clearance: Maintain at least two feet of clear space around the entire unit. Trim back any shrubs, weeds, or overhanging branches.

• Snow and Ice: In the winter, gently brush away any snow that has drifted against the unit. A heat pump buried in snow can’t extract heat from the air.

Diagnosing Common Heat Pump Problems

If the basic checks didn’t fix the heat pump, it’s time to look at the specific symptoms. Understanding what’s happening is crucial before you attempt to fix a heat pump with a more complex issue.

Heat Pump Not Heating

One of the most common complaints is a heat pump that runs but doesn’t provide warmth.

• Defrost Mode: Heat pumps periodically run a defrost cycle in winter to melt ice off the outdoor coils. During this brief cycle (usually 5 to 15 minutes), the unit temporarily switches to cooling mode, and you might feel cooler air from the vents. This is normal.

• Low Refrigerant: If the system is low on refrigerant due to a leak, it can’t transfer enough heat to warm your home.

• Reversing Valve Issue: The reversing valve is what switches the unit between heating and cooling. If it’s stuck, the heat pump might be trapped in cooling mode.

Heat Pump Blowing Cold Air

Getting a blast of cold air when you expect heat can be unsettling.

• Thermostat Fan Setting: As mentioned, a fan set to “On” instead of “Auto” is a primary culprit.

• Defrost Cycle: This is a normal function where the system briefly reverses to melt ice from the outdoor unit.

• Dirty Filter or Coils: Severe airflow restrictions can lead to lukewarm air that feels cold.

• Refrigerant Leak: A significant refrigerant leak will prevent the system from producing any meaningful heat. A proper diagnosis is the first step to fix a heat pump that isn’t warming your home.

Heat Pump Not Cooling

In the summer, your heat pump acts as an air conditioner. If it’s not cooling, the causes are often similar to heating issues.

• Incorrect Thermostat Settings: Double check that it’s set to “Cool” and the temperature is set below the current room temperature.

• Dirty Coils: Grime on the indoor or outdoor coils acts as insulation, preventing the system from removing heat from your home.

• Refrigerant Leak: Just like with heating, low refrigerant means the system can’t effectively absorb heat from inside and release it outside.

Deeper Dive: When Simple Fixes Aren’t Enough

Sometimes, the problem lies with a specific component failure that requires more than a simple adjustment. Working on other home appliances too? Check our LG appliances error codes to decode common issues fast.

The Unit Won’t Turn On at All

If there’s no power and no response, the issue is often electrical.

• Power Supply: Beyond the breakers, ensure any power switches near the indoor and outdoor units are turned on.

• Thermostat Signal: A dead thermostat or faulty wiring can prevent the signal from ever reaching the heat pump.

• Failed Starter Capacitor: A key symptom of a bad capacitor is a clicking or humming sound when the unit tries to start, but the fan or compressor never kicks on. The capacitor provides the jolt of energy needed for startup. For these more complex electrical issues, it is always safest to call a certified technician to fix the heat pump.

The Heat Pump Runs Constantly

A heat pump that never shuts off is working too hard and wasting a lot of energy.

• Extreme Weather: On the coldest or hottest days, it’s normal for a heat pump to run for longer periods.

• Airflow Issues: A clogged filter or blocked vents make the system run longer to try and reach the set temperature.

• Refrigerant Leak: Low refrigerant reduces efficiency, forcing the system to run continuously to keep up.

• Undersized Unit: If the heat pump is too small for your home, it may never be able to satisfy the thermostat, especially in extreme weather.

My Heat Pump is Short Cycling

Short cycling is when the unit turns on and off in rapid, short bursts without completing a full heating or cooling cycle. This puts a lot of wear on the compressor.

• Overheating: A dirty filter or blocked coil can cause the system to overheat and shut down on a safety switch.

• Thermostat Placement: If your thermostat is in direct sunlight or near a heat source, it might get a false reading and shut the system off prematurely.

• Oversized Unit: A heat pump that is too powerful for your home will cool or heat the space very quickly and shut off, leading to frequent cycles.

Strange Noises or Smells

Your heat pump should operate with a relatively quiet hum. Loud or unusual sounds and smells are warning signs.

• Hissing: This often indicates a refrigerant leak.

• Grinding or Screeching: These sounds can point to a failing motor or worn bearings. Shut the unit off immediately to prevent further damage.

• Banging or Clanking: A loose part, like a fan blade, could be hitting something inside the unit.

• Burning Smell: An electrical burning smell is a serious issue that could indicate an overheating motor or wiring problem. Turn off power at the breaker immediately. A dusty smell when you first turn on the heat for the season is usually normal.

• Musty Smell: This often suggests mold or mildew growth on the indoor coil or in the ductwork.

Special Case: Heat Pump Not Working in Cold Weather

Heat pumps are very efficient, but their heating capacity diminishes as outside temperatures drop.

• Reduced Efficiency: A standard heat pump can struggle when temperatures fall near or below freezing. It has to work much harder to extract heat from the frigid air.

• Auxiliary Heat: Most heat pump systems include a secondary heat source, often called auxiliary or emergency heat. This is typically a set of electric resistance heat strips that turn on automatically to supplement the heat pump when it can’t keep up.

• Icing Up: It’s normal for the outdoor unit to develop a thin layer of frost in cold, damp weather, which the defrost cycle handles. However, if the unit becomes encased in a thick block of ice, it’s a sign of a problem, such as a blocked unit, a bad defrost control, or low refrigerant.

Knowing how to fix a heat pump often starts with understanding these cold weather behaviors.

The Best Fix: Preventive Maintenance

The easiest way to avoid having to fix a heat pump is to prevent problems from happening in the first place. A well maintained heat pump can last 15 years or more. Thinking about turning your DIY skills into a career? Read why many pros say the trades are the real path to success.

• Change Filters Regularly: This is the most important DIY task.

• Keep the Outdoor Unit Clean: Gently hose off the outdoor coils once or twice a year (with the power off) to remove dirt and debris.

• Schedule Professional Tune Ups: Have a certified HVAC technician inspect your system annually. They can clean components, check refrigerant levels, test electrical connections, and catch small issues before they become major breakdowns. Regular maintenance is often required to keep your manufacturer’s warranty valid.

Know Your Limits: When to Call a Professional

While DIY troubleshooting is great, some jobs are strictly for the pros. Knowing when to put down the tools and pick up the phone is key to staying safe and avoiding more expensive repairs.

You should call a professional to fix your heat pump if you encounter: Not sure which category your symptoms fit? Post details in our Questions & Answers forum.

• Refrigerant Issues: Handling refrigerant requires an EPA 608 certification by law. It’s a hazardous substance and the system needs to be charged precisely. If you’re interested in how technicians get certified, platforms like SkillCat offer fully online EPA 608 training and certification.

• Electrical Problems: If a breaker keeps tripping or you suspect a bad capacitor, motor, or wiring, call a pro. Capacitors can hold a dangerous electrical charge even when the power is off.

• Loud Mechanical Noises: Grinding, screeching, or banging sounds point to internal mechanical failure that requires expert diagnosis.

• The Problem Persists: If you’ve gone through all the basic troubleshooting steps and the system still isn’t working right, it’s time for a professional opinion.

If troubleshooting your system sparks an interest in how it all works, you might have a knack for the HVAC trade. For inspiration and community, see Women in the trades you need to follow right now. For those looking to turn curiosity into a career, SkillCat’s mobile first training platform provides an affordable and flexible path to becoming a certified technician.

Frequently Asked Questions to Fix a Heat Pump

1. Why is my heat pump blowing cold air in heat mode? This could be a normal defrost cycle, which is temporary. If it persists, it might be due to a clogged air filter, low refrigerant, or a problem with the reversing valve. Also, check that your thermostat’s fan is set to “Auto,” not “On.”

2. How often should I change my heat pump air filter? You should inspect it monthly and change it every 30 to 90 days, depending on your filter type and household conditions (like pets or dust).

3. Is it normal for my heat pump to run all the time? During extreme cold or hot weather, it’s normal for a heat pump to run for long periods. However, if it runs constantly in mild weather, it likely points to an issue like a dirty filter, low refrigerant, or an improperly sized unit.

4. Can I add refrigerant to my heat pump myself? No. Handling refrigerant is illegal without an EPA certification and requires specialized equipment. If your system is low, it means there is a leak that must be found and repaired by a professional first.

5. What does a clicking sound from my heat pump mean? A single click when the system starts or stops is usually normal. However, if you hear repeated clicking and the unit fails to start, it often signals a failing starter capacitor or another electrical control issue. If this guide saved you a service call, rep the trades with our We Build the World T‑shirt.