Why Is My Air Conditioner Not Working After Winter? [8 Causes & Fixes]

If winter is over, can summer be far behind? To prepare for scorching summer days, we will test whether the air conditioner is working properly in advance.

You are not alone if your air conditioner stops working after the winter season. I’ve been through it and understand how concerned you’ll be.

Calm down! Things might go better than you think. For example, I have made it turn on again within a matter of minutes.

An air conditioner that stops working after winter is often because its power supply is cut off, the filter is too dirty, the drain hose is clogged, or the condenser coil is covered with debris. 

There is more than that. I will detail all the reasons and solutions in the following sections, so keep reading!

Ready? Let’s dive right in.

1. The power supply is cut off

Since air conditioners are electrical appliances, they will not turn on if you have cut off the power supply. As you haven’t used it for a long time, you may forget what you did on your AC last year. 

It is possible that you or an HVAC technician have flipped the emergency shutoff switch near the outdoor unit or that a power surge tripped the circuit breaker or blew a fuse.

What to do?

You can fix it by turning on the circuit breaker or the emergency shutoff switch. Some air conditioners will be reset by doing this.

2. The thermostat needs to be adjusted

Air conditioners won’t kick in if you don’t turn your thermostat to the cooling mode or if the set temperature is reached. Perhaps you just forgot to make any adjustments after the heating season.

Besides, in rare cases, your air conditioner stops working because it can’t receive the signal from the thermostat.

What to do?

Examine your thermostat’s settings and ensure that the cooling mode is turned on. You can also reset it by pressing and holding the reset button for five seconds.

3. It is cold outside 

When spring comes, you can’t wait to test if your AC is working. However, your AC may malfunction when it is cold outside. Typically, it is not recommended to run an AC below 60 degrees. 

The lubricant oil remains thick, and the air cannot warm up the evaporator coil. All of these will have an impact on the performance of your air conditioner and may even cause it to fail.

What to do?

Wait until the temperature rises above 65 degrees before attempting again.

4. Debris stuck in the condenser 

dirty condenser coils

Condenser units sit in the elements. Naturally, the twigs, stones, feathers, or other particles will get inside and affect the normal operation of your machine. 

When too much debris gets stuck in the condenser, it can result in overheating in the compressor, which will shut down the entire unit as a failsafe. If you hear a rattling noise from the outdoor unit and it stops working, this is most likely the cause.

What to do?

After removing the outer panels, use a vacuum cleaner or your hands to remove anything that may interfere with the performance of your appliance.

5. Dirty filter 

dirty ac air filter

Not everyone will give their AC an annual maintenance check after each cooling season. The dirty filter will stay there for months, and the mold and mildew will proliferate happily. 

Beyond that, some air conditioning systems will share the filter with the furnace.

As you know, clogged filters will impede the airflow. The reduced airflow causes the compressor to work harder and shut down when it overheats. 

What to do?

As long as the filter is cleaned, this issue will be resolved. All you have to do is take it out, clean it with water, and then replace it. If the filter is too filthy to clean, a new one can be installed.

6. Clogged drain hose

During winter, something like a bug or rat may get into the hose by accident and die inside.

When you turn on your machine a few months later, the drip pan will quickly fill up with water due to the clogged hose. Your air conditioner will stop working once the float switch in the pan is activated.

What to do?

While it is a bit disgusting, it is easy to solve. You can disconnect the hose and use a wire brush or vacuum cleaner to dislodge the dead animal or buildups.

To kill the bacteria and mold, pour some vinegar or bleach through it.

7. Refrigerant leak

refrigerant leak

Imagine that the refrigerant has begun to leak last summer, but you don’t notice it. With time, more and more refrigerant leaks out until it makes your AC stop working the following summer.

In addition, if the insulation is damaged, the cold winter weather can cause the coil to crack.

What to do?

There are a few ways to identify if the refrigerant level is low, including a hissing noise, an increase in the electricity bill, or a frozen evaporator. 

If you have any doubts that the refrigerant in your air conditioner is running low, contact a certified HVAC professional. They will locate the leak, repair it, and then recharge your air conditioner.

8. Malfunctioning blower 

The blower will continue to operate in the winter for those who have central air conditioning. It will soon wear out because every part has a lifecycle.

The fan blades may be bent, or the motor is failing. Either of these could make a loud clicking noise, and it will lose the capability to pull sufficient air in.

What to do?

You should leave it to a technician if you lack the necessary expertise. They will diagnose the issue and repair or replace the blower.

To summarize

You will feel frustrated if your air conditioner can’t be turned on after winter. Luckily, you can often get it solved by checking the power supply, cleaning the air filter, or removing large particles stuck in the condenser.

However, there are times when you will require the assistance of a professional.

Hopefully, this guide has assisted you in identifying the issue and getting your air conditioner back up and running.

If you want your AC to function well in the upcoming season, your best bet is to give your appliance maintenance before and after each cooling season.

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested a lot of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.