Air Conditioner Not Cooling? 13 of the Most Common HVAC Problems and How to Fix Them

Is your air conditioner not cooling anymore? Don’t sweat it, this could actually be a quick fix. Keep reading to learn more about the most common HVAC issues and how to solve them.

1. Air Isn’t Coming Out Of The Registers

If you notice that there is no air coming out at all. This could mean that the fan outside of your unit is not running. This sounds like a big scary problem, but actually, this is a simple problem you want to have.

What this means is that the breaker is just tripped and needs to be reset. This could also mean that you have another even easier problem: the blower belt just needs a replacement.

Other solutions to this issue could be a problem with the control board, wiring, thermostat, or your condensate pump reservoir is full.

2. Air Conditioner Isn’t Coming On At All

If your air conditioner won’t come on at all, this could mean you have a problem with your thermostat. Just set your thermostat to cool and turn down the temperature. Next, check your electrical panel and see if you have a blown fuse or if your breaker is tripped.

You’ll want to also check for any power supply issues by checking out the wires. You also might want to look at your furnace power and then switch the thermostat if you have any problems.

3. Air Conditioner Not Cooling

If your air conditioner seems to be running but it isn’t cooling, relax, because this is one of the most common air conditioner issues. The only problem is there are a number of possible reasons for this.

Here are some common solutions.

Dirty Filter 

It doesn’t matter what kind of air conditioner you have, if you have a clogged filter, this limits the airflow. When this happens the efficiency of your AC is reduced, and there is less of a chance that the air gets cooled.

If you haven’t cleaned your filer in your portable or window air conditioner, do that and also make sure you check it periodically. You should change your central AC filters at least once a month, especially if you’re running your system a lot and or you have pets.

It’s Too Sunny Inside For Your Window AC

If you have a window AC and that window gets direct sunlight in the heat of the day, it’s going to be a lot harder to clean your home. If you are able, try to move your AC unit to a less sunny spot.

If you can’t move your AC unit, then you should keep your curtains and shades down during the day so you can block the sunlight so your house won’t heat up. The same is true if you have central AC.

Warm Air Is Leaking In

If you have a window AC, be sure to check the seals around your unit to make sure that the hot air from the outside isn’t leaking in and the cold air isn’t seeping out. You might need to reseal your unit with weather stripping.

Window AC Is Vibrating

It’s no surprise that air conditioners make a lot of noise like the whir of the fan or the sound of the compressor turning on and off. These noises are actually normal, what isn’t normal is if you hear a vibrating noise.

A vibrating sound could mean that your unit wasn’t properly installed. You want to make sure your unit is securely sitting on the window. You should also review your installation instructions in your owners manual to double check that you didn’t skip a step when installing your AC window unit.

Thermostat Setting

If your central AC has a smart or programmable thermostat, you are able to control the temperature in your home to a more comfortable one when you’re home and put it up higher when you are not home.

If the temperature seems off, you should make sure that your thermostat isn’t being exposed to any direct sunlight. Direct sunlight can cause it to register at the wrong temperature.

Dirty or Blocked Registers 

If you have a forced cooling and heating system, you want to make sure that you are regularly vacuuming the registers and make sure that you get rid of any dust buildup. You also want to make sure that no objects or furniture is blocking the airflow through your registers.

Plants Crowding the Compressor

Your outdoor compressor for your central air conditioning needs to have decent airflow to properly work. So make sure there is at least two to three feet of space between your compression and any structures or plans. There should also be about five feet of space between the top of your unit and any trees above.

Annual Checkup

You also want to make sure that your unit gets an annual inspection by an HVAC (heating, ventilation, and air conditioning) technician. This annual check-up can catch any serious issues before they get worse and leave you sticky and sweaty in the heat of the summer. An HVAC technician will check all of your moving parts including the refrigerant and will also recharge your system if it needs it.

4.  You’re Low On Refrigerant

Often if your air conditioner isn’t cooling properly it could be because you are low on refrigerant. This could mean that you have a leak or your system is undercharged.

You’ll want to check for any leaks before you add any more refrigerant. Often problems with leaks will keep happening and they can be harmful to the environment.

5. Air Conditioner Is Blowing Hot Air

There is nothing more annoying than when your AC blows hot air. You wanted an air conditioner, not a heater! Usually, this is a problem with a dirty air filter, and this can cause flow issues.

Make sure that your outside unit is running first. Also, be sure to check if there any debris or leaves that are messing up the flow. Another issue could be that you are low on Freon.

6. Unit Is Leaking

If you have a leaky unit, this could be because air conditioning makes condensation which is usually drained. However, sometimes. the pipes can be blocked or leak or the condensate pump just stops working.

If this happens, you want to try to clean your condensation drain pipe and clean your system of algae with bleach. You’ll also want to check the electrical connection to your condensate pump.

7. Compressor Won’t Run

If your compressor isn’t running that could mean that there is a defective start capacitator, burned wire or just a defective compressor. If it won’t reset then you’ll want to adjust your refrigerant charge, check the capacitor, clean the condenser coil, and or replace the compressor.

8. Air Conditioner Never Turns Off

Even when it is super hot out, your air conditioner should still be turned off from time to time. If your AC is constantly running, this could be a problem with your fan. Turn your thermostat fan off and see if it stops. You also might want to check your relay switches and refrigerant levels.

9. Air Conditioner Is Making A Strange Noise

It’s normal for air conditioners to be noisy, but if you hear a sound you don’t recognize that could be an issue. Strange AC noises, such as a squealing sound, might indicate a belt issue. Your AC’s belt might not be aligned properly or it might need to be replaced.

If you hear a grinding noise, that could mean there is an issue with the motor’s bearings. If you hear a popping or pinging, that could be a loose flap of metal in the ductwork. If you hear a rattling noise that could mean you need to tighten your cover panels.

10. Fan Isn’t Working

If the fan for your outdoor unit isn’t turning on, then your AC is likely not properly cooling. You should press the reset or overload button and try to reset your unit. Or if your unit is turned off, then try to spin your fan blades clockwise.

If the blades can freely spin, you might have a problem with you capacitor and it might need to be replaced.

11. Condenser Isn’t Running

If your condenser isn’t running, first you want to make sure it’s getting power. You’ll want to verify that your unit is plugged in and there isn’t a tripped circuit breaker or a blown fuse.

If your condenser isn’t running, you might have problems getting the cooling control signal from your thermostat. So check the oil level and safety switches.

Also, check for refrigerant pressure. If the refrigerant has leaked, then the low-pressure safety could have been switched.

12. Unit Constantly Turns On and Off

If you find that your AC comes on and off repeatedly, then there is a signaling problem. Typically your condenser unit is blocked or dirty or your evaporator is dirty. You’ll want to check both for obstructions and give your unit a good cleaning to clear any debris.

13. The Coil Is Frozen

If you have a frozen coil then your AC is working overtime as your house is staying hot. Check for any airflow issues like a dirty filter. Also, check your blower fan and refrigerant level.

Fix Your AC

Now that you know why your air conditioner not cooling, try these hacks first to see if you can solve the problem. If that doesn’t work, you will need to call a professional. For more homeowner resources, check out our blog.