2 Stage Air Conditioner Problems

It may be difficult to decide what type of air conditioner to purchase. Generally, you may be lost between a single-stage air conditioner and a two-stage AC unit.

You may also be considering variable-speed air conditioners. The following are some of the key problems of a two-stage air conditioning system.

What is a two-stage air conditioner? 

A two-stage air conditioner is a special type of furnace with three operating states. It can either be high, low or off. When a two-stage compressor runs, the cycle between high and low repeats. So, a two-stage air conditioning system lets you set the temperature at which it should operate.

A single-stage AC system is different. It has only two states of operation. It is either off or operating at a maximum state. When a single-stage air conditioner is running, it is always at maximum or full blast. A

variable speed air conditioner is different from the two. You can adjust the compressor speed of a variable speed AC system according to the airflow. This makes it easy to create a comfortable environment at home.

Two-stage air conditioner problems

1. High initial costs 

A two-stage air conditioner costs much more than a single-stage air conditioner. Purchasing a two-stage air conditioner costs hundreds of dollars. The initial cost of a single-stage air conditioner is much lower.

Many people note the difference in initial costs between these two air conditioners. Single-stage units cost hundreds of dollars less than two-stage AC units.

The difference in initial cost between these two air conditioners is significant. But remember that a variable speed air conditioner costs much more than the two.

Although a two-stage AC is a more efficient system than a single-stage AC, the cost difference is huge. You are likely to consider this difference in initial costs when purchasing a new air conditioner.

Some contractors say that savings usually offset the high initial costs in the energy costs. However, this is not always the case. A two-stage AC unit does not provide huge savings in energy costs enough to offset the high initial cost.

2. Higher operational costs 

Maintaining two-stage air conditioners is costlier than single-stage air conditioners. The high maintenance costs are because for different reasons. For example, a two-stage AC is prone to breaking down.

This is because it tends to run longer than single-stage systems. A two-stage air conditioner has low, high, and off settings. A single-stage AC has only two settings: off and on. So, a two-stage compressor is more prone to breakdowns than a single-stage one.

Also, it may not be easy to find spare parts for a two-stage system. The actual repair works on a two-stage system may take quite a long, even when you get them. You will pay more for maintaining a two-stage AC than a single-stage compressor.

3. Complex repairs 

Repairing a two-stage compressor is more difficult than a single-stage compressor. A two-stage compressor is vulnerable to breakdowns because it runs longer than a single-stage one.

This is the price that you have to pay for the convenience of a two-stage AC unit. Although it is more efficient and convenient than a single-stage one, it breaks down often.

The repairs of a two-stage air conditioner take a long time. Therefore, if the technician charges you hourly, you will pay more for a two-stage compressor. In addition, the technician will take a longer time repairing a two-stage AC unit than a single-stage AC unit.

Repairs on a variable-speed air conditioning unit are even more complex. The variable speed AC has a more advanced technology than the two.

You need a well-trained technician to understand the variable speed technology. So, when choosing from single, two, and variable speed units, consider the repairs.

4. Real-world performance

Many people consider two-stage units efficient air conditioners. They also believe that a two-stage air conditioner is quiet and can service a larger area than a two-stage AC.

Manufacturers of two-stage compressors emphasize these features. But are they true? Let us start with energy efficiency.

Energy efficiency means that a two-stage air conditioner should use less fuel than a one-stage unit. This should be under similar operating conditions.

A two-stage air conditioner will consume only 0.4% more fuel than a single-stage unit in real-world performance. However, if you are using electricity, then things change. Two-stage air conditioners consume 11% more electricity than single-stage air conditioners.

A variable speed air conditioner will be less energy efficient. So, a single-stage system is more convenient than a two-stage one. A two-stage unit may save you some money in energy costs. But the money may not be much.

5. They are not completely continuous. 

Two-stage air conditioners are effective in reducing cold air spots in your home. So, they generally improve indoor air quality. This is because they have three states of operation. But do two-stage air conditioners improve indoor air quality because they run non-stop?

In reality, your two-stage air conditioner runs on the high mode 25% of the time that it is on. When it is not running on the high mode but on, it is on the low mode. This effective alternation helps to distribute heat evenly across large areas. It also helps avoid cold air building up in some areas in your home.

A two-stage air conditioning system does not run completely continuously. But it runs on the low mode for a long time. Then, it switches to the high mode when there is a need to provide extra heat.

6. Lack of longevity – more prone to breakage

Manufacturers claim that two-stage air conditioners have a longer lifespan than single-stage compressor units. But evidence from users shows that this is not true. Single-stage air conditioners last longer than two-stage air conditioners. The reasons for this are many.

First, two-stage air conditioners tend to break down more often than one-stage units. When the air conditioning system breaks down, it tends to die off. Two-stage air conditioners break down often because they run for a long time.

Some people even believe that manufacturers deliberately make two-stage air conditioners vulnerable to breakdowns. If the machines break down often, consumers will have to replace them often.

But there is no evidence that two-stage air conditioners are more delicate than single-stage AC units. A single-stage unit may have a longer lifespan than the other two furnaces.

Two-stage vs. one stage air conditioner

 There are clear differences between a two-stage and a one-stage air conditioner. One of the main differences between these two types of air conditioners is power settings.

A single-stage air conditioner has only two power settings: on and off. When a single-stage AC system is operating, it is at full capacity. A two-stage air conditioner has three power settings: high, low, and off.

When you switch on your two-stage air conditioning system, you can choose between low and high. A two-stage AC unit is usually on low mode 25% of all the time when it is on.

Ideally, it should spend 75% of the period in low mode. But in reality, this is not always the case. The high and low cycle repeats are not perfect.

The difference in power settings between these two types of air conditioners is important. Many contractors argue that two-stage air conditioners are more energy-efficient than single-stage AC units.

Two-stage air conditioners switch to the high mode when the temperatures are low. When the temperatures are slightly high, the air conditioner switches to the low-speed mode. Contractors argue that this mode of operation is important for saving energy.

Alleged benefits of two-stage air conditioner

Contractors repeatedly argue that two-stage air conditioners have many other benefits apart from energy efficiency. For example, they argue that two-stage air conditioners are far better than single-stage. But what are the benefits of two-stage air conditioners? Are they worth it?

Many contractors say that two-stage air conditioners create a comfortable indoor environment. The dual temperature control feature of a two-stage AC unit is critical. It helps to create a uniform temperature around the entire indoor environment.

This is not the case with single-stage units. A single-stage compressor has only two temperature control stages. When it is on, it is operating at its maximum level. So, the thermostat cannot accurately read the house’s temperature level.

The air around the AC unit tends to be hotter than that away from it. As a result, cold air spots develop in some room areas. Sadly, the thermostat cannot detect this problem.

But this is not a problem with two-stage air conditioning systems. The high and low-temperature control features prevent the formation of cold air spots in the house.

Contractors also say that two-stage air conditioning systems circulate air for longer. When the two-stage compressors repeatedly alternate between high and low, they minimize energy bills.

The two-stage heating and cooling system help to lower your electric bill in the long term. The long-term energy savings associated with two-stage air conditioners is an amazing advantage.

Does a two-stage furnace save energy for real?

Manufacturers say that two-stage air conditioners lower energy bills. The complex technology of the two-stage air heating and cooling system is useful.

It helps to control their energy consumption. It also enables the compressor to switch between the first and second stages.

The consistent switching between the first and second stages helps minimize the amount of fuel that a two-stage AC system utilizes.

For example, the unit switches to low instead of switching off when the temperature is medium. Also, when the temperature changes, the two-stage AC unit may switch to the low mode.

But a two-stage air conditioner may not always utilize less energy. The constant switching between the first and second stages helps create a comfortable environment.

But it does not necessarily make the HVAC system use less energy. A two-stage AC unit may consume less energy than a single-stage unit. This may not translate to long-term energy savings.


Is it worth it to get a two-stage air conditioner?

If you are not worried about the downsides of a two-stage air conditioner, it is worth getting one. The downsides are the high initial costs and the tendency to break down. Remember, you may not get great savings in energy costs. But you will have a more comfortable home. This is because of the way a two-stage air conditioner functions.

Is a two-stage air conditioner worth it in California?

A two-stage air conditioner is worth it in California. Having such a furnace is more convenient for the conditions in California. In addition, you can adjust the fan speed between high and low. This will allow you to adjust your air conditioning system according to the weather.

Does a two-stage air conditioner run all the time?

A two-stage air conditioner does not run all the time. Two-stage air conditioning systems spend about 25% of the time in the high mode. This is when they are on. The rest of the time should be spent in low mode. But in reality, the compressor of a two-stage air conditioner does not run all the time.

How do you troubleshoot a two-stage air conditioner?

You can troubleshoot a two-stage air conditioner by manually switching between the first and second stages. Begin by setting the compressor to the first stage mode. Measure the amp and record the reading. Next, switch the compressor to the second stage slowly. Take the amps reading. The amp reading in the second stage should be between 25% and 30% more than in the first stage.


Two-stage air conditioners create a comfortable indoor environment. The three-settings feature lets you adjust them according to the weather. But two-stage air conditioning units have multiple problems. They tend to break down faster than single-stage AC units. Also, they do not always run as the contractors say.