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Is your AC condenser unit blowing cold air outside instead of warm/hot? If so, you are probably not getting cooler air inside your home. This article will examine the top 10 common issues I typically encounter during my service calls that will likely cause your outdoor condenser unit to blow cold air.
Main Reasons Why an AC Condenser Blows Cold Air Outside
- Dirty air filters
- Leaking refrigerant
- Stuck Reverse cycle valve (If you are using a heat pump)
- A defective compressor capacitor
- Blocked Condensor Coils
- Malfunctioning Thermostat
- Issues with the Blower Motor
- Incorrectly Sized AC Unit
- Damaged Ductwork
- Low Ambient Temp.
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Cold Air Outside Issues & Solutions
When running an air conditioner, the outside condenser is designed to release heat from indoor air. However, if you notice your outdoor unit blowing cold air, something could happen. The following are some of the possible reasons for that:
1) Dirty Air Filters
A dirty air filter can cause your outdoor condenser unit to blow cool air instead of warm air. Air filters play an essential role in the operation of your air conditioning system. Before getting to the evaporator coil, they screen substances and objects from the air.
However, if the air filter gets dirty and clogged, air won’t be able to flow freely into the evaporator coil. This can cause two things to happen:
- Airflow is restricted from the evaporator coil. Because of that, the refrigerant will not turn into gas. Instead, the evaporator coil will freeze.
- When air filters are clogged, air won’t be able to pass through them freely; instead, dirty air will bypass them and deposit dirty debris on the evaporator coil. This will make it hard for the refrigerant to absorb heat from your indoor air. The liquid and cool refrigerant will then run through to the condenser coil. Instead of releasing heat, the condenser will release cool air.
How do I fix dirty air filters?
If you have not changed the air filter in a while, this is the time to replace it or clean it if it’s washable. Generally, air filters are supposed to be changed or cleaned at least once for about 2 months. Check the status of the air filter, and if it’s dirty, take note of the specifications before getting a new one.
If your air filter is in good working condition and there is no issue concerning your outdoor unit blowing cold air, then let’s go to the next step of our troubleshooting.
2) AC System Has a Leaking Refrigerant
If the refrigerant has leaked out of your air conditioner system, this will cause your condenser unit to blow cold air. That is because no heat has been absorbed from your indoor air to be released outside by your condenser unit.
The refrigerant in the air conditioning system helps transfer heat between your indoor and outdoor air. It’s a medium through which heat is extracted from your home and disposed of outside.
It is worth noting that an air conditioning system is a closed system where the refrigerant level is expected to remain the same throughout the life of your air conditioner. When the levels go down, that means there is a leak that needs to be sealed. In the worst-case scenario, you may need to replace the evaporator/condenser coil, but that is rare.
How do I fix a leaking refrigerant?
If you believe you have low refrigerant in your AC system, it is best to call a licensed HVAC technician or local HVAC experts to come and examine your AC system.
Usually, a technician will verify the refrigerant charge and pinpoint the leaks in the ac system.
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After sealing the leaks, the refrigerant (how to tell if your AC used Freon) can be recharged into your AC system. Otherwise, if leaks are not sealed, the refrigerant can leak out again in a matter of days.
3) Stuck Reverse Valve (If you have a heat pump)
A stuck reverse valve could be the reason for your ac outdoor unit blowing cold air.
Reverse valves switch between the cooling and heating modes to help the heat pump work as an air conditioner and a heater.
After a long time of use, the reverse valve can malfunction or get stuck in either one of the modes. When the reverse valve gets stuck in the heating mode, your outdoor unit won’t blow warm air but cold air.
You can quickly tell if your reverse valve is stuck in a single operating mode by trying to run your heat pump in both modes, one at a time.
Let’s say you try to run it in heating mode. If the heat starts coming through, then the heat is working. And typically, in heat mode, the outdoor unit should blow cold air outside.
Now try running your heat pump in the cooling mode. If the condenser unit continues blowing cool air and no cool air comes into your home, it’s a good sign that the reverse valve is defective.
How do I fix a reverse valve that is defective?
If you believe you have a defective reverse valve, it’s best to call an HVAC professional to come and take a look. A reverse valve is replaceable and may need to be replaced. A technician should be able to recommend what to do next.
4) Defective Compressor Capacitor
A defective compressor capacitor can make your condenser outdoor unit to blow out cold air. Newer air conditioners come with dual capacitors that power the compressor (on one side) and the fan motor (on the other).
If one side of the capacitor that serves power to the compressor dies, the other part that powers the fan motor can continue working, and the fan will be blowing air when you run your air conditioner.
The refrigerant will not circulate the coil because the compressor won’t be running. And that will not transfer heat inside your home to the condenser unit. This is why your outdoor unit fan will blow cold air.
How do I fix a defective compressor capacitor?
Just like many other parts of an AC system, a compressor capacitor is replaceable. You can either call an HVAC technician to come and install a new one or do it yourself by purchasing a new capacitor and swapping it out. The steps to replace one are below:
- Safety First: Always ensure the power to the AC unit is switched off at the breaker before doing any work on it to avoid the risk of electric shock.
- Access the Capacitor: The capacitor is typically located in the outdoor unit of your AC system. You’ll need to remove the access panel on the unit, which is usually held in place with screws.
- Identify and Inspect the Capacitor: The capacitor is a cylindrical component that may be silver or a different color. Be sure not to touch it immediately after removing the panel, as capacitors can hold an electrical charge even after the power to the unit is disconnected. Use an insulated tool to discharge the capacitor by placing it across each set of terminals. You can then inspect the capacitor. It likely needs replacing if it’s bulging, leaking, or shows signs of damage.
- Note Specifications: Before removing the old capacitor, note its specifications, usually printed on the side. This information will be crucial when purchasing a replacement.
- Disconnect Wires and Remove Old Capacitor: Carefully disconnect the wires connected to the capacitor, making sure to note which wires connect to which terminals for the correct installation of the new capacitor. You can then remove the old capacitor.
- Install New Capacitor: Connect the wires to the new capacitor in the same configuration as the old one. Secure the new capacitor in place.
- Replace Access Panel: Once the new capacitor is installed, replace the access panel and secure it with the screws you removed earlier.
- Restore Power: Turn the power back on at the breaker.
- Test the System: Turn on your AC system and monitor it to ensure it’s operating correctly. The outside unit should now expel warm/hot air, not cold.
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5) Blocked Condenser Coils
The condenser coils dissipate heat removed from the air by releasing it outside the building. If they’re dirty or blocked by debris, they cannot effectively release this heat, causing the system to work inefficiently and potentially blow cold air outside.
Blocked or dirty condenser coils can cause your air conditioning (AC) unit to blow cold outside air. The condenser coil in the outdoor unit plays a vital role in the cooling process. It’s where the refrigerant releases the heat absorbed from your indoor air. If the condenser coils are blocked or dirty, they can’t effectively remove this heat. This blockage can cause the system to work inefficiently and potentially blow cold air outside.
The condenser coils are a series of tubes filled with the refrigerant. They are surrounded by metal fins that aid in heat transfer. Over time, these fins can become clogged with dirt, leaves, grass clippings, and other debris, reducing their effectiveness.
This debris can insulate the coils, preventing them from releasing heat effectively. When this happens, the refrigerant cannot cool down as much as it should before it moves back into your home. This results in the refrigerant not absorbing as much heat from your home’s air, leading to the condenser unit blowing cold air outside.
How Do I Fix Blocked Condenser Coils?
Regularly clean the condenser coils and remove debris around the outdoor unit to allow for proper airflow. For thorough cleaning, it’s best to hire a professional.
6) Malfunctioning Thermostat
A malfunctioning thermostat can cause your air conditioning (AC) unit to blow cold outside air. The thermostat is the control center of your HVAC system, allowing you to set the desired temperature and operating mode. If the thermostat is not functioning correctly, it can send incorrect signals to your AC system, leading to various issues, including the outdoor unit blowing cold air.
When the thermostat is not reading or communicating the correct temperature, it may not signal the AC system to turn on and off at the appropriate times. As a result, the compressor might not run when it should, causing the refrigerant not to circulate through the coils as it should. This disruption in the heat absorption and release process can lead to the condenser unit blowing cold air outside.
How to Fix A Malfunctioning Thermostat
Check your thermostat settings first to make sure it’s set correctly. If it is, but you’re still having issues, you may need to replace the thermostat. It’s recommended to call a professional to handle this.
7) Issues with the Blower Motor:
Issues with the blower motor in your air conditioning (AC) unit can also lead to the outdoor unit blowing cold air. The blower motor powers the fan that circulates air through the ducts in your home and across the evaporator coil. If the blower motor is malfunctioning, the heat exchange process can be disrupted, leading to your condenser unit blowing cold air outside.
The blower motor drives the fan that circulates air through your home and across the evaporator coil, where it gives up its heat to the refrigerant. If the blower motor is not functioning correctly, the airflow can be reduced or stopped altogether.
This lack of airflow can cause the evaporator coil to freeze, reducing its ability to absorb heat from your home’s air. Consequently, the refrigerant moving to the condenser unit is cooler than it should be, resulting in the condenser unit blowing cold air outside.
How to Fix Issues with the Blower Motor:
8) Incorrectly Sized AC Unit
It could short-cycle if your AC unit is too large for your space. This means the unit turns on and off quickly and does not run long enough to remove heat from the air effectively.
How to Fix an Incorrectly Sized AC Unit?
Unfortunately, replacing the unit with one properly sized for your space is the only fix for this. A professional can help you determine the correct size.
9) Damaged Ductwork
The ductwork in your home distributes cooled air. If it’s damaged, leaks, or improperly installed, it can disrupt the normal flow of air and heat, causing the unit to blow cold air outside.
How To Fix Damaged Ductwork?
It would be best if you had a professional inspect your ductwork for leaks or damage. They can then seal or repair the ductwork as necessary.
10) Low Ambient Temperature
If the outside temperature drops too low, the AC unit can struggle to extract enough heat from the air, resulting in cold air being expelled.
How to Fix Low Ambient Temperature
During periods of extreme cold, it may be necessary to use supplemental heat sources. Some AC units also have a ‘low ambient kit’ which allows them to operate effectively in colder temperatures. If you live in a cold climate, consider speaking to a professional about installing one of these kits.
|Dirty air filters||Replace or clean air filters regularly|
|Leaking refrigerant||Call a licensed HVAC technician to seal leaks and recharge refrigerant|
|Stuck Reverse cycle valve||Consult an HVAC professional for repair or replacement|
|Defective compressor capacitor||Replace the faulty capacitor|
|Blocked condenser coils||Hire a professional to clean the condenser coils and remove debris|
|Malfunctioning thermostat||Check thermostat settings or replace it if necessary|
|Issues with the blower motor||Seek professional assistance for repair or replacement|
|Incorrectly sized AC unit||Replace the AC unit with the correct size|
|Damaged ductwork||Have a professional inspect and repair the ductwork|
|Low ambient temperature||Consider supplemental heat sources or install a low ambient kit|
In conclusion, an AC condenser unit blowing cold air outside can be due to various reasons, ranging from dirty air filters and refrigerant leakage to more complex issues like a malfunctioning thermostat or problems with the blower motor. It’s crucial to identify the root cause of the problem to apply the correct solution. Regular maintenance, such as cleaning air filters and condenser coils, can prevent some of these issues. However, more technical problems like a defective compressor capacitor, malfunctioning thermostat, or issues with the blower motor require professional intervention.
Remember, an AC unit is a complex piece of machinery, and some repairs can be dangerous if not handled properly. Therefore, it’s best to consult with a professional HVAC technician when in doubt. Doing so can ensure that your unit is operating effectively and efficiently, providing you with the comfort you need in your home.
Understanding these top 10 reasons why an AC condenser unit may blow cold air outside is the first step towards troubleshooting and resolving such problems. With this knowledge, you can ensure your unit’s longevity and optimal performance, keeping your home cool and comfortable.
HVAC tech with over 30 years of experience. Retired and doing repair work on the side around Madison County, AL.