Why is my air conditioner running but not cooling my house?

Why is my air conditioner running but not cooling my house?

If your air conditioner is coming on inside and outside and you are wondering, why is my air conditioner running but not cooling my house then this article is for you.

There are multiple reasons your A/C is running but not cooling your house. Here are some common issues that will cause your AC unit to run but not keep up with the heat load in the house.

*DISCLAIMER – Read the disclaimer below.

Reason 1. Clogged air filter.

dirty air filter keeping the ac unit from cooling
dirty air filter keeping the ac unit from cooling

The first thing to check is your air filter. If your air filter is really dirty it will prevent airflow and your air conditioner won’t cool very well. If you check it and it’s really dirty pull it out temporarily. If the air coming out of the ducts starts to blow cold in about 5 minutes then that may have been the problem.

If your filter was dirty you may still want to check the rest of your HVAC system to ensure that’s all that was dirty.

Reason 2. Dirty evaporator coil.

An extremely dirty evaporator coil is possibly another reason the air conditioner runs but doesn’t cool the home adequately. If your air conditioner evaporator coil is really dirty it will need to be cleaned.

Some coils are so dirty they are almost beyond cleaning. Most evaporator coils can be cleaned and restore the ability of the coils to absorb heat.

Why is my air conditioner running but not cooling my house
dirty evaporator coils

CLICK HERE to read my article about how to clean your evaporator coils.

After your coils are cleaned the system will be able to absorb the heat and do its job.

Reason 3. Dirty condenser coil.

If your AC is running but not cooling the house then you may want to check that all of the coils on your condenser are clean and free of obstructions. Having a dirty condenser coil will prevent the AC condenser from doing its job.

Without getting extremely complicated the condenser releases heat from the refrigerant that has traveled from inside the home’s evaporator coil. If the condenser coil is dirty air can’t flow over the condenser coils and the heat transfer does not take place as well as it should.

Dirty evaporator coil causing warm air to blow
Dirty Condenser Coil

Reason 4. Slightly low on refrigerant.

Another reason the system is running but not cooling is that the system is low on refrigerant. If the system isn’t icing up at the condenser or the evaporator coil then the system may be a little low on refrigerant.

If the system isn’t icing up then it’s not low enough to freeze up but low enough to affect the ability of the system to remove heat from the home.

An easy way to determine if this is the case without having any gauges is to go outside and inspect the refrigerant lines at the condenser.

Touch the larger size condenser line. If the refrigerant is low it will be dry, not cold, with no condensation.

A system that has adequate refrigerant will have a large suction copper line that feels like a soda can coming out of an icebox.

As you can see there are a lot of issues you can check on your own.

Here are some that will require a little more knowledge.

Reason 5. Dirty blower motor.

Having a clean blower motor on your system probably doesn’t seem very important. When a blower motor hasn’t had a professional cleaning in a while. Dust will impact the high-velocity spinning blades and become impacted and hard.

After the dust impacts the blades it reduces the ability for the blades to catch and move the air correctly.

Why is my air conditioner running but not cooling my house
A dirty blower motor can cause multiple problems for an HVAC system.

Even small amounts of impacted debris on the fan blades will reduce the life of the blower motor and reduce the ability of the blower fan to move air in the home.

Most blower motors require the removal of electrical wires from the control board and other mechanical things that must be removed in order to be properly cleaned.

This should be done by a professional that has worked on and has experience shutting off all the power and making sure to not damage or bend any of the components during removal.

Reason 6. The condensate safety overflow switch.

The primary and secondary drain lines should be routinely cleaned out and checked to ensure the free flow of the condensation coming from the evaporator coil.

When air flows past the evaporator coil it carries dust and other elements in that air. When that air hits the evaporator coil some of that debris gets in the coil and in the evaporator coil drain pan. This may be why is my air conditioner running but not cooling my house, and not the emergency pan but, the internal drain pan inside the evaporator coil enclosure.

Slidell la air conditioning service and repair

Algie and other dust will collect in the drain pan and work their way into the drain line.

If a professional company is servicing your equipment they should be doing what’s required to ensure the drain pan and primary drain line don’t clog up.

Living in Slidell, La adds to the number of algae build in the evaporator coil. I have found that due to the proximity of Lake Ponchartrain routine maintenance on the evaporator coil and cleaning of the evaporator coil pan and drain lines are required.

Reason 7. Bad Capacitors

Your system may have a few capacitors that need to be checked to make sure they are still strong enough and haven’t gone below the manufacture’s suggested replacement.

The capacitor will have a sticker on the side of it that tells you what size in Microfarads.

For example, if you have a dual run capacitor it may be a 40/5 MFD capacitor. The 40 MFD is used to assist the compressor and the 5 MFD is used to assist the condenser fan motor. The sticker will give an allowable % below the original rating that is allowable.

For example, if your capacitor is 40/5 and you use the tester and it only reads 30/2 then the capacitor should be changed out. Even if the condenser is still operational you should change out the capacitor to prevent any of the other components from being damaged due to overload.

routine services your a/c and heating equipment needs

I prefer to test capacitors under load. Testing in that manner should only be done by a trained professional. However, there are capacitor testers that make it fairly simple for a mechanically inclined person who has the time to check the capacitor.

The indoor blower motor will often have a single-run capacitor also. Sometimes they are fairly hard to access and may even require the blower motor to be removed in order to test it.

routine services your a/c and heating equipment needs

Having your capacitors checked and replaced before they completely go out is something that needs to be checked on a routine basis.

Reason 8. The Contactor is bad.

On a routine check of the A/C system, you need to check the contactor to make sure it’s not sticking. Sticking can occur when the thermostat calls for cooling and the metal contacts are so damaged they overheat and stick together.

routine services your a/c and heating equipment needs
The contactor will stick

When they stick the condenser may keep running even when the inside has reached the set temperature inside. This can cause numerous problems and premature failure of the compressor.

Why is my air conditioner running but not cooling my house. Reason 9 may be (High Static pressure).

If your static pressure hasn’t been checked before it may reveal inadequate return airflow. The return air is where the air flows through the filter and gets conditioned by the A/C system.

The Top 10 Routine Services Your A/C And Heating Equipment Needs.
routine services your a/c and heating equipment needs

If your HVAC system has inadequate return airflow then another return air will need to be added to allow your system to operate to its full potential.

A static test may reveal the supply ducts are not large enough. In some cases, they may be too large.

If your service provider is checking the static pressure often then you most likely already know if major issues exist.

If this information provided any value as to why is my air conditioner running but not cooling my house please leave a comment below.

*DISCLAIMER ! WARNING, This Video and information on this channel are for trained and certified technicians only. It is for educational purposes only. Under no circumstances should anyone who is not qualified or have the required permits or licensing attempt to use any information on this channel or video to try and repair an HVAC or electrical system on their own. The opinions and methods I use are my opinions and I give no guarantee of any type of outcome. In other words, if you are not a trained and certified technician you should not attempt any repairs on your own. You should hire a licensed professional to do the work.  

***Income & Affiliate Disclaimer. If you purchase a product or service from one of the links on this page you should assume I earn an affiliate commission. Meaning I earn money because you purchase through one of my links. You should also assume that by clicking on my links you may receive email communications from me. 

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