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My Air Conditioning isn't working, what should I do?

Updated: Nov 3, 2021

Is your air conditioner not working or not heating / cooling properly?

In most cases, the reason an AC unit is not cooling is due to simple problems such as dead batteries in the remote controller, a tripped breaker, or a disconnect switch accidentally turned off. Once these items have been checked, it’s time to look at the AC unit itself to determine where the problem is.


What to Check First Before calling in an Technician to evaluate your system, there are several things that homeowners and building managers can check when the air conditioner is not working.

Check Air Filter

The air filter is responsible for cleaning the air in the AC system and protecting the heat exchange coil. The filter is typically located in a slot between the return air duct and the fan on a ducted system or behind the front casing panel on a Wall Mounted or Ceiling Cassette type. When the air filter gets dirty, this can cause poor air flow within the system, disrupting the flow of air to the coils, thus causing them to freeze. The result? Your air conditioner will blow warm air, or no air at all.


Make sure to check your air filter every three months. Clean or replace the air filter if necessary. Air filters are available from us if required, we would just need the make and model number of your indoor unit


To clean the filter, simply turn off the unit and open the front cover and then remove the filter as shown below. Clean using a vacuum cleaner and lightly wash with warm soapy water and then shake off before replacing. Turn the AC back on.




Watch how to clean your filters





Check Your Controller Settings Make sure to look at the remote or wall mounted Controller, as this is the central control station of your system. Make sure the digital controls show that the AC is set to “ON” and either “COOL”/ “HEAT” or if appropriate “AUTO”. It is also important that the temperature is set low enough to activate the air conditioner in cooling or high enough for Heating (Depending on Season). A temperature setpoint of 21 / 22 deg C should be fine in most environments.

Check Any Disconnect Switches Make sure all switches are turned on. The first switch should be indoors, near your unit . The second will be found outdoors near the condensing (outdoor) unit .. Be cautious when checking the outdoor disconnect switch as the box may contain high voltage. Call for professional help if you’re not sure whether the switches or breakers are working correctly.


Reset Circuit Breakers Once you’ve verified that all the switches are set to “on,” it’s time to head to your circuit breaker panel. If the breaker is tripped, try resetting it to see if that solves the problem. It’s important to consider that breakers trip for a reason so if it happens again, there’s likely to be an overloaded circuit or other electrical problem that needs professional help.

Check Airflow Airflow can also be restricted by overgrown greenery or other obstructions to the outdoor unit. Make sure to keep any plants or shrubs near the outside AC system cut back to allow for an easy flow of air.

If you see ice on the outdoor unit, your air conditioner may not be working properly or at all because it is frozen. To remedy this problem, turn the entire system off and check or change the indoor filter. Then, allow several hours for all the ice to melt completely and try restarting the system to see if it works. If it’s still not cooling, turn it off again and contact an HVAC professional who can check for problems with the refrigerant.

Check for a Refrigerant Leak A refrigerant leak should not be repaired by you, unless you happen to be an HVAC professional. However, if you check around the Condensing unit and can see oil, it may indicate a leak. Contact a licensed HVAC expert to have your unit inspected. 

Check Condensing Unit The air conditioner condensing unit is the part of your air conditioner that’s located outside your house and is the part that rejects heat to atmosphere. When the condenser coil gets dirty, the air conditioner’s job gets harder. Throughout the spring and summer, your condenser coil may become clogged with everything from leaves to dirt and grime. Depending on the state of your air conditioner, your AC unit may have to work very hard to keep your home cool.


What you can do: Clean your air conditioner condenser coil. Cut the power to the air conditioner. Use a vacuum cleaner (shop vac type is ideal) to suck leaves and weeds from the unit. Spray the coil (at the back of the unit) of the ac unit with a hose (not a power washer), restore power. 

If you’re not comfortable cleaning your own air conditioner condenser coil, hire a professional to do the work for you. Your HVAC professional will give your air conditioner a service and clean your condenser coil for you. 

Keep debris away from the condenser to prevent the unit from getting dirty. Pull nearby weeds and discard them. Avoid planting any shrubs or plants nearby, especially if those shrubs or plants shed leaves or needles that will eventually blow into your condenser.  Promote air flow around the unit. Do not place a fence or barrier within two feet of the air conditioner unit to keep air flowing smoothly. 

When to Call for Help Your Controller checks out, all the switches and fuses appear to be working correctly, the filter has been cleaned or a clean filter has been installed, and you’re still not getting cold air from the air conditioner. At this point, there are several components that could be the source of the problem, and all of them require a knowledgeable service technician to diagnose and repair. Also, if you hear unusual noises when the system is cycling on and off, there could be a problem with the indoor fan. Keep in mind that most systems will make some noises, so you’ll be listening for anything that’s abnormally loud or otherwise strange compared to the usual pops and dings. A burning smell coming from anywhere in the system means it’s time to shut it down and call for assistance. 

At CEK Air Conditioning, we have the knowledge and experience to diagnose and repair all air conditioner makes and models. Our technicians always stay on top of the latest technology in the industry so you can be sure the job will be done right the first time. Contact us on 01795 342272 to schedule an appointment today.


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