Is Your Heat Pump Steaming Outside? Defrost Mode Explained for Rogue Valley Winters

As the temperature drops on a particularly cold winter day, your family cozies up inside to enjoy the warmth and comfort of your home. Suddenly, you notice the steam rising from your heat pump’s outdoor unit and an unusual noise. In a panic, you start to worry about whether your heat pump is going to die during one of Rogue Valley’s cold snaps.

The good news is that this type of heat behavior is relatively normal. Your heat pump is simply protecting itself from colder temperatures.

To help you avoid stress this winter, we’ll dive into what defrost mode is, why it happens, what it looks like, and which red flags you need to call Rogue Valley Heating, Cooling, & Electrical for emergency heat pump repair services and expert troubleshooting.

Quick Answer: What Is Heat Pump Defrost Mode?

Defrost mode is a completely normal cycle. It involves your heat pump temporarily switching modes to melt the frost on your outdoor coil.

This cycle occurs during the heating season when cold air and humidity are present. In these conditions, frost can build up on the coil. Fortunately, your unit is able to handle this on its own, so you don’t need to shut the heat pump off or make any changes.

Why Does Frost Build Up on the Outdoor Unit in the First Place?

While Rogue Valley rarely experiences extreme temperatures, it can still get fairly cold. When you switch your heat pump to heating mode, the unit pulls heat from the outdoor air. As a result, the outdoor coil becomes cold.

If outdoor temperatures are near freezing and the humidity level is high enough, moisture in the air can freeze on the coil. Because Rogue Valley is known for its wet winters, there is plenty of moisture in the air to cause frost. As soon as our mild winter days get cold enough, the heat pump can ice up.

How Defrost Mode Works

The defrost mode is a protective setting that keeps your heat pump working at its best in cold temperatures. It functions through a few essential mechanisms.

The System Briefly Switches To Melt the Frost

First, the heat pump temporarily reverses its operation to warm up the outdoor coil. As it does this, the frost on the coil starts to melt. You may notice water vapor and runoff as the frost melts.

The Outdoor Fan May Stop Temporarily

While this can vary between different systems, many systems will stop the outdoor fan from running. This is completely normal and helps to speed up the defrost process.

Your Home Stays Comfortable Using Backup Heat

While the defrost cycle is underway, your home may use auxiliary heat or a backup heating option. In most cases, this involves electric strips. Because of this, you may notice minor changes in how your home’s air feels while this cycle is in effect.

What You Might Notice During Defrost Mode (And Why It’s Normal)

If your heat pump’s defrost mode is running, there are a few common things you may notice.

• Steam: You’ll typically see steam rising from the outdoor unit while the defrost cycle is going. While this looks fairly dramatic, it just means that warm moisture is hitting the air as the frost melts off.
• Unusual Noises: If you hear a clicking or whooshing sound, don’t panic. Both of these noises are normal when the heat pump switches modes.
• Stopped Fan: While some units can vary, it’s fairly normal for the fan to stop during defrost mode. Afterward, it will restart like normal.
• Dripping Water: As the frost melts off of your unit, you may notice water dripping or running off the unit.
• Cooler Air: Although it doesn’t happen all the time, some backup heat sources and heat pump systems may produce cooler air during defrost mode.

How Long Should Defrost Mode Last?

Most defrost cycles are relatively short and take just a few minutes to complete. However, the cycle can last longer if there are colder temperatures, higher humidity levels, or more frost buildup. You’ll generally see longer, more frequent defrost cycles on cold, damp mornings. During periods of dry cold, defrost cycles are less common.

Defrost Mode vs. Emergency Heat: Not the Same Thing

Although aux heat may kick on during your defrost cycle, defrost mode and emergency heat are different settings.

Defrost Mode

Defrost mode is an automatic, short-term cycle that is a normal part of wintertime heat pump operations. It lasts for a few minutes and gives the outdoor unit a chance to melt any frost or ice. Once the defrost cycle is complete, the unit can function more efficiently.

Emergency Heat

Meanwhile, emergency heat is a manual setting on your thermostat. It does not automatically switch on. Typically, homeowners only use emergency heat if their heat pump has to be turned off or is incapable of functioning properly. Unless a heating, ventilation, and air conditioning (HVAC) professional tells you to do so, you should not be using emergency heat all of the time.

When You Should Be Concerned: Red Flags To Watch Out For

Defrost mode is a normal part of your heat pump’s wintertime operations. While you don’t need an HVAC technician when normal defrost operations are going on, the following signs are red flags that you should reach out for professional help.

• The outdoor unit is covered in a solid block of ice.
• You hear loud screeching, banging, or grinding noises.
• The ice never clears off of the coil.
• The defrost cycle seems to run non-stop or has significantly more cycles than normal.
• You noticed both ice buildup and weak airflow in your home.
• The breaker trips whenever the system runs.
• You noticed water pooling in an area that could cause a refreezing hazard or other damage.

Common Causes of Excessive Frosting or Defrost Problems

If you experience excessive frosting on the outdoor unit or problems with your defrost mode, there are a few potential issues that could be at fault.

• Airflow Restrictions: A blocked vent or dirty filter could be restricting airflow.
• Refrigerant Levels: If there is a leak or low refrigerant, it stops the heat pump from functioning effectively.
• Excessive Debris: Leaves, mud, and debris can end up clogging the outdoor unit.
• Fan Motor Malfunctions: If the fan motor is faulty, it can potentially lead to excessive frosting and defrost issues.
• Faulty Sensors, Reversing Valves, and Control Boards: Faulty components can hinder the HVAC unit’s operations.
• Improper Installation or Sizing: If the system is sized incorrectly or is improperly installed, it can cause it to function less efficiently.

What You Can Do at Home To Help Your Heat Pump Through Winter

To help your heat pump function at its best, there are a few simple steps you should take.

• Clear away snow and debris from the outdoor unit so that there is plenty of airflow on every side. For your safety, do not clean inside the unit.
• Change your air filter regularly.
• Check your vents to make sure they are open and unobstructed.
• Set realistic temperature settings on your thermostat. Major temperature jumps throughout the day can cause more backup heat usage.
• Schedule your seasonal maintenance appointment to ensure your system is functioning at its best.

What a Professional Check Includes (And Why It’s Worth It)

When you reach out to Rogue Valley for a professional heat pump inspection, we’ll support you through the following measures.

• Confirm that your defrost cycle is functioning correctly.
• Check your outdoor coil to make sure it is in good condition and has proper airflow.
• Inspect the sensors and controls for potential issues.
• Verify your refrigerant levels and performance.
• Look for potential signs of wear that could cause unexpected HVAC failures.
• Make sure your backup heat is ready for when it’s needed.

Through our heat pump inspection, we can help you spot minor problems before they escalate. Besides avoiding costly repairs and inconvenient breakdowns, our expert HVAC technicians can help your family enjoy better peace of mind this winter.

FAQs

Over the years, our team of HVAC technicians has fielded a few common questions about defrost mode operations and heat pump repairs.

Is it normal for my heat pump to steam in winter?

Yes, it is. If the temperature gets cold enough, the heat pump’s coils can develop ice. When this happens, the heat pump reverses direction temporarily so that it can heat up the coils. As the ice melts, you will likely see some steam.

While defrost mode is perfectly normal, there are situations where you should call for help. Any burning odors, dark smoke, unusual noises, or non-stop cycling are signs that something is wrong with your heat pump.

Why did my outdoor fan stop running?

There are a few reasons why this can happen. If defrost mode or emergency heat mode is on, the fan may stop running automatically as a part of the system’s design. It may also stop running if there is a mechanical issue, such as a faulty capacitor, a bad fan motor, electrical malfunctions, or debris blocking the fan.

Why is my heat pump blowing cooler air inside for a few minutes?

During the winter, a heat pump can blow cool air if it is switching into defrost mode. This causes the heat pump to reverse direction, so it can gradually warm your outdoor coil. Once the defrost cycle is complete, you should feel warm air coming from your vents again.

How often should my heat pump go into defrost mode?

New units will often go into defrost mode every 30 to 90 minutes. Typically, these heat pump cycles last for around 5 to 15 minutes.

Modern heat pumps can detect when the defrosting process is finished or needs to be extended. With older units, the defrost mode may be timed and automatic.

No matter what type of unit you have, the defrost mode should not be happening constantly. If defrost mode is happening every 20 minutes, your heat pump needs to be professionally inspected.

Can I pour hot water on the outdoor unit to melt ice?

Yes, you can use hot (not boiling) water on your outdoor unit to melt excessive ice. To ensure your safety, always turn off the unit at the breaker before pouring any hot water.

Pouring hot water is a temporary measure for frozen coils. If your coils need this type of treatment, there is an underlying problem that needs to be diagnosed and repaired.

What’s the difference between Aux Heat and Emergency Heat?

Aux heat is a secondary heat system designed to back up the heat pump when the heat pump is struggling, such as during extreme cold snaps. Emergency heat is also a secondary system that is intended to be used during times when your heat pump is incapacitated. While they rely on the same secondary system, the main difference is how they are used. Aux heat is an automatic supplement for extreme weather, and emergency heat is a last-resort replacement when your heat pump is unable to function properly.

Should I turn my heat pump off during defrost?

No, you should not. The heat pump needs to be on to complete the defrost cycle. If you turn it off, the heat pump will remain frozen and may be unable to work when you turn it back on later.

When does icing mean I need repair?

There are a few situations where icing indicates immediate repair needs.

• The ice has been on your unit for multiple days.
• Airflow to the unit is restricted.
• The unit is completely iced up.
• Ice is forming on your indoor components as well.

Keep Your Home Warm and Toasty This Winter

If you notice steam coming out of your heat pump, you don’t have to worry. In most cases, this is a sign your heat pump is in defrost mode. By allowing defrost mode to run, you can protect your heat pump and ensure it can operate efficiently. Steam, dripping water, and temporary sound changes are normal signs that happen during defrost mode.

However, heavy ice, weak heat, and constant defrosting are indications of a potential problem. If something feels off about your heat pump unit, you should schedule service right away to avoid unexpected breakdowns and emergency repairs.

Stay comfortable this winter by scheduling your heat pump maintenance today.