Delonghi Portable Air Conditioner Troubleshooting & How-to Guide
Tips & Tricks

Delonghi Portable Air Conditioner Troubleshooting & How-to Guide

The summer heat can be frustrating, and the worst thing has a malfunctioning air conditioner. Delonghi portable air conditioners are among the most prominent in the market. Their portable air conditioners have cooling options varying from 6,500 to 14,000 BTUs, a slightly wider range than most. However, these appliances are not without fault.

Most Delonghi AC users have complained about the unit failing to blow cold air, shutting off intermittently, failing to dehumidify, error codes, lack of evaporating water, and others. However, not all air conditioner problems require professional repairs. Instead, our troubleshooting guide will help you determine the cause of the issues and how to prevent similar problems in the future.

How to use a Delonghi portable air conditioner

Remove the appliance from the packaging and ensure the product is complete, undamaged, and all accessories are present. Note that varying installation processes depend on the model, but here is a general guide.

Assembly tips

There are two options to install your Delonghi portable air conditioner:

Window installation

This is the most popular way to install a portable air conditioner. First, you attach the hose and use the provided window kit to vent the warm air. Then, when the temperature cools or you want to move the unit to another room, you simply detach the window kit and wheel the air conditioner to the other room.

  • Find the exhaust hose and two hose adaptors.
  • Screw one of the hose adaptor to one end of the air exhaust hose.
  • Then screw the other hose adaptor onto the exhaust hole on the back of the air conditioner unit.
  • Insert the exhaust hose(the end without an adaptor attached) into the adaptor on the back of the AC.
  • Then add the window outlet on the other end of the hose.
  • Open your window slightly and place the window outlet in place.

Wall installation

For this method, you must permanently vent the portable air conditioner through a hole in the wall. This is ideal for shops and offices. You can also use this method to install a portable AC in a windowless room.

Follow the hose assembly in steps 1-4 above for permanent installation. Then find a good position for your hose. Then drill a hole 134mm in diameter through a door or wall to allow it to vent outside. The end of the exhaust hose should securely fit in the hole.

Operating tips

  • After installing your new Delonghi air conditioner, wait at least one hour before turning it on for the first time. This allows the refrigerant in the unit to settle from the movement of installing it.
  • Install the plug in a working power outlet.
  • Switch on the portable air conditioner by pressing the power button on the control panel or remote control.
  • Select the operating mode of your air conditioner. The standard options include; air conditioning mode, dehumidifying mode, eco real feel function, and fan mode. Then the heating mode is available in specific models.
  • Choose the ideal temperatures. The best temperature for an adult sitting still in the room is about 22 degrees; if you’re exercising, a cooler temperature will be more comfortable. Try not to set the thermostat below the outside temperature.
  • Select the airflow speed between low, medium, and fast.
  • Use the timer to ensure your rooms are always cold while saving money by using less electricity.

Why is my Delonghi portable AC not cooling?

The purpose of your Delonghi portable AC is to cool down the room’s temperature by blowing cold air into the room and pushing the heat. Here are some reasons your unit is running but not blowing cold air.

Check the AC mode setting.

The first thing to do when you notice your Delonghi portable AC is not cooling is to check if the AC mode is correct. These ACs have three settings; Cool, Dry and Fan.


Ensure the AC mode is on “Cool,” then see if it starts cooling again. If it doesn’t, continue with troubleshooting.

Clogged air filter

The air filter in your Delonghi AC helps trap dust and dirt so that you can breathe clean air. But if you do not clean this air filter regularly, it accumulates dust. Consequently, the fan will run, but cold air will not blow into the room. A clogged air filter will also lead to a smelly air conditioner.


Remove the filter from your unit and clean it with mild detergent and water. Then allow it to dry completely before reinstalling it into the air conditioner. Remember to clean the air filter once every month. You may have to clean it more frequently if you reside in a very dusty place.

Dirty condensation coil

The condensation coils in your portable AC act like the heat exchanger. It absorbs the heat from the room and changes it into vapor thanks to the refrigerant flowing it at low pressure and low temperature.

Then it releases cooler air into the room. Unfortunately, when these coils become dirty, they cannot effectively absorb the heat from the room. Therefore, your room will not get cool enough.


To fix this, find the condensation coil in the top compartment of your portable AC. If the coils are dirty, try to clean them using a damp microfiber cloth or use a shop vac.

Low refrigerant

Air conditioners have refrigerant, a fluid in the condensation coils that absorbs heat from the room and provides cool air. If the refrigerant starts leaking, your AC cannot effectively cool your room.


If you notice leaking inside your AC, call an HVAC expert to fix the leak and refill the refrigerant. Too much or too little refrigerant will cause the air conditioner to malfunction.

Blocked exhaust hose

The fan blows the hot air from your unit through the exhaust hose. Since warm air blows over the cold condensation coil, the exhaust pipe can become humid and cause the growth of algae, mold, and mildew.

These fungi can overgrow and block hot air from flowing out of the AC unit. If the exhaust hose is kinked or blocked, the hot air will flow back into the unit and heat the air coming back into the room.


Inspect the hose for blockages or kinks. You can either clean the exhaust pipe with white vinegar or replace it. You have to repeat the cleaning process every month to prevent buildup.

Faulty thermostat

The thermostat in your Delonghi portable AC helps monitor the room’s temperature and sends the data to the AC, which adjusts accordingly. If your set a specific temperature, the thermostat will try to maintain this temperature by controlling the flow of electricity to the compressor.

So if the thermostat becomes defective, your portable AC will not maintain the desired room temperature.


First, ensure the thermostat batteries are working. If not, try replacing them. Dirt and dust particles can also accumulate on the thermostat, preventing it from reading the temperature correctly.

Clean your thermostat, then check if the issue has resolved. If the problem persists, you may have to replace the thermostat with the help of an HVAC professional.

Incorrect AC size

The size of your AC unit is very important to cool your space adequately. The size of the AC unit depends on its cooling capacity and not its physical dimensions. The cooling capacity is the amount of heat your portable AC unit can remove in one hour.

Manufacturers use BTU(British Thermal Units) to measure the cooling capacity of air conditioners. Generally, the more BTUs, the bigger the room and air conditioner will keep cool.

So if an AC unit has many BTUs for a space, the unit will cool the room too quickly, but this may be energy inefficient. On the other hand, if a unit has fewer BTUs for a space, it will not sufficiently cool the room’s ambient temperature.


Similar to other home appliances like electrical heaters, the size of your room determines the size of your air conditioner. Delonghi manufacturers also specify the room size an air conditioner will keep cool.

You will have to measure the length and width of your room, calculate the space’s area, and then match the product with the appropriate unit. Of course, if you’re unsure, you can always call an HVAC expert to advise on the best capacity.

The chart below shows the many BTUs you will need for different room sizes with a standard 8-foot ceiling.

Room size in square feetBTUs needed

Note: Choose the higher option if your room size falls between excellent BTUS ratings. The chart is not exact; other factors may increase or decrease the number of BTUs required. Besides the size of the room, selecting the right portable air conditioner depends on other factors like climatic conditions, the room’s purpose, and the number of people staying in the room. For instance, rooms with poor insulation or heat-emitting appliances will require models with slightly more BTUs.

The room is not sealed.

Your Delonghi portable AC will not cool the room properly if the doors and windows are open. Increased temperature from the outside can overwhelm the AC unit until it stops working. Sunlight coming through the windows can also increase the room temperature.


It’s important to close the room’s doors, windows, and blinds before running your portable AC. Note that portable ACs only cool spaces with a specific temperature. So if the room temperature is

95°F, the Delonghi air conditioner will find it hard to keep up.

How do I reset my Delonghi air conditioner?

You may have to reset your Delonghi portable AC after a power outage or when you suspect some electrical issues. Resetting your Delonghi will clear all your saved settings and any bugs that could be causing issues. Below are all the ways you can reset Delonghi portable air conditioners.

Reset button

The older Delonghi portable AC models have a reset button on the remote control; some later models have a reset button under the inside unit or outer side grill. To reset these units, you simply press the reset button.

Hard reset

The newest models do not have a reset button, so that they will require a hard reset. Here’s how to do this:

  • First, press the power button to turn off the portable air conditioner.
  • Then unplug the unit from the AC.
  • Leave the portable air conditioner off for about five minutes.
  • Then plug it back into its power outlet.
  • Next, press the power button to turn the unit on.
  • Finally, turn on the thermostat to allow the air conditioner to start a new cooling phase.

Why is my Delonghi AC blinking HL?

The HL error message on your Delonghi portable AC means that the unit is full of water and requires draining. To clear the error code;

  • Go to the back of your unit, insert your hand through the door just above the word PULL and then pull out the water tank.
  • Disconnect the tank’s drain hose and position the end into a jug
  • Replace the spout cap with the drain hose cap.
  • Then remove the can and allow the water to run off until it’s empty.
  • Replace the cap, reposition the hose properly and close the water tank.

All Delonghi portable air conditioner error codes and their meaning

Delonghi air conditions have a self-diagnosis system that identifies malfunctions in the unit and display an error code on the AC display. The following are all the error codes on Delonghi air conditioners, their meanings, and how to fix them.

Error codesMeaningsPossible solutions
LT or LEFrost prevention mode activatedDelonghi portable AC has a frost protection device to avoid excess ice formation. In addition, the AC restarts automatically when the defrosting process completes.
CFFilter is dirtyReplace the limescale filter
PFProbe failure or a damaged sensorContact your local authorized service center
F1The indoor unit room sensor is disconnected.The unit is functioning normally in air mode.Reset the unit. If the error code persists, contact customer services.
H1High room temperatureClose windows, doors, and blinds.

Delonghi air conditioner mode symbols: their meaning

Several modes you can choose on your AC will help you achieve the best results under certain conditions. Here are the modes in a Delonghi portable AC and their meanings.

  • Air conditioning mode: This is suitable for hot, humid weather when you need to cool and dehumidify the room.
  • Auto fan mode: The unit automatically chooses the most suitable fan speed depending on the temperature set on the digital display.
  • Dehumidifying mode: This mode is ideal for reducing moisture in the room.
  • Fan mode: You don’t need to attach the air hose when the AC unit is in this mode.
  • SMART mode: The appliance will try to recreate the ideal conditions in the room. The unit automatically decides whether to operate in air conditioning, fan, or standby mode depending on the environmental conditions detected in the room.

Delonghi portable air conditioner is not evaporating water.

Delonghi portable ACs have a self-evaporating technology that empties the water catching tray automatically, thus eliminating the need for manual emptying of the unit.

Instead, the appliance recycles about half of the condensed water and uses it to cool off the inner condenser coils, allowing the unit to operate more efficiently.

It then evaporates the remaining water into the outside air and hot air through the exhaust hose at the back of the unit.

So if your AC fills with water too quickly, the evaporation technology may fail. Here are the main reasons why your portable AC is not evaporating water.

High humidity

If you’re experiencing high humidity in the room, the condensation in the AC will build up faster than it can recycle and disperse outside. Under such conditions, you must drain the water to ensure the unit continues working manually.

For example, suppose you live in an area with high humidity, such as Louisiana or Texas, with an average relative humidity of 75%. In that case, more water will collect in your portable AC drain pan.

Dirty air filter

A clogged air filter will block the air from coming out of your portable AC. As a result, the airflow rate will reduce, and less air will pass over the evaporator coils. As a result, the evaporator coils will freeze the moisture in the air and keep dripping into the drain pan.

First, check if the filter reset LED light has turned on, then clean the filter with a shop vac. If it’s too dirty, clean the filter with lukewarm water, then allow it to air dry before inserting it back.

The AC is new

If you recently purchased your Delonghi portable AC and it’s not evaporating water, it’s highly unlikely that it’s a technical issue. However, suppose you haven’t air-conditioned your space in a while.

In that case, the new AC will have to dehumidify the room’s walls, furniture, floors, ceiling, and other contents as it cools the air until the humidity lowers to normal levels. This will result in a large amount of water accumulating in the drain pan.

Instead, try closing the doors and windows and allow the unit to finish dehumidifying the room.

Defective condensate pump

An effective way to remove condensate is to install a condensate pump. The condensate pump will direct water accumulating in the drain pan to your desired location.

So if you have a condensate pump and the drain pan keeps filling up, there is a problem with the pump, or the drain hose is blocked or kinked.

First, check the drain hose for blockages and bends. Then check the condensate pump. Try priming the pump; fill the tank with water, and turn on the power switch. The pump will start, and the water will start circulating in the unit.

If the pump doesn’t start, check the power cable and ensure it has been plugged in. If the cord is plugged in, check the circuit breaker and reset it if necessary.

Faulty blower fan

The fan in your portable AC helps to circulate air in the unit. If the fan is not running at the optimum RPM or not running at all, the cool air will stay longer in the appliance, resulting in the frosting of the evaporator coils.

When the coils freeze, the AC compressor stops automatically until all the ice melts. No evaporation will occur when this ice is melting, and the drain pan will fill up with water quickly.

When inspecting the blower fan, look for damaged fan blades, faulty fan motor, or problems with other electronic components such as the switch, relay, or control board.

Clogged evaporator coils

The Delonghi portable AC has heating coils(condenser coils) and cooling coils(evaporator coils). Both coils need to be clean for the air to flow through them. But if they have clogged with dirt, less air will pass through them; ice will develop and eventually melt into the drain pan.

You will need to clean the coils with a soft-bristled brush or use warm water and mild detergent.

Delonghi portable air conditioner is not turning on

Here’s what to do when your Delonghi portable AC doesn’t turn on.

Check for power supply.

First, ensure the power cord is correctly plugged into the outlet, then inspect the cord for damages. If the cord is okay, check the wall outlet and circuit breaker. Next, try resetting tripped switch at the breaker box. If that doesn’t work, check if the fuse has blown and replace it if necessary.

The water reservoir is full.

Delonghi ACs have a water level sensor that notifies you when the water reservoir is almost full. If you ignore this alert, the portable AC will turn off and will not turn on until your drain the water reservoir.

Frozen coils

When ice develops on the evaporator coils, the AC automatically shuts off until all the ice melts. This is a safety feature that protects your AC’s compressor. First, all the ice to melt, then consult with an HVAC professional for troubleshooting.

How to clean and maintain a Delonghi portable air conditioner

Delonghi portable air conditioners are durable appliances; however, they require regular cleaning and maintenance to ensure the work is efficient and for longer. Before cleaning or maintenance, turn off the unit, wait a few seconds, then unplug it from the power outlet. Here’s how to clean and maintain your Delonghi AC.



  • Use a slightly damp cloth to clean the exterior of your AC. Do not wash the appliance with water as it could damage its electrical components. Do not also use solvents or harsh cleaning products.

Air filters(available in all models)

  • Clean the air filters every week to ensure the air conditioner works efficiently. To clean the filters:
  • Pull out the intake grille.
  • Remove the dust filter.
  • Use a vacuum cleaner to clean off the dust and dirt on the filter.
  • If the filter is very dirty, soak it in lukewarm water and rinse it several times.
  • Allow the AC filter to dry completely, then replace it with the AC.
  • Replace the filters at least twice per month and more often during the summer.


Always check the coils to ensure they are not accumulating dirt. To clean the coils, use a damp cloth or soft-bristled brush and gently brush off the dirt. If the coils are too dirty, use the coil cleaning solution available at your local hardware store.

Silver ion filters and electrostatic filters(available in specific models)

  • Take out both filters from the AC.
  • Then use a vacuum cleaner and medium power to dust them off.
  • You can wash the silver ion filter in lukewarm water. Leave it to air dry, then replace it.
  • You should never wash the electrostatic filter, but you should replace it at least once every two seasons.


  • Empty any water left in the appliance before putting it in storage. To drain the tank: pull out the tank, remove the can and drain out the water left in the tank.
  • To drain the internal tank, replace the spout cap with the drain hose + cap, place a container near the spout, remove the cap and allow the water to run off. When complete, replace the cap.
  • After draining the appliance, turn it on and set the fan-only mode. Allow the AC to run for about 30 minutes. This process dries any water remaining inside the appliance.
  • Turn off and unplug the AC.
  • Disconnect the exhaust hose and condensate the drain hose.
  • Then keep your AC and its components in a cabinet to keep off dust. Finally, ensure not to bend any hoses and pipes.
  • Do not cover the AC with plastic.

Delonghi portable air conditioner compressor is not working.

The purpose of a compressor in an AC is to absorb heat from the room and compresses the cool, low-pressure, gaseous refrigerant until it becomes hotter and achieves higher pressure.

The warmed refrigerant heats up further and converts the hot air from a gaseous state into liquid, leaving cooler air to flow back into the room. So if the compressor fails, the AC will not blow cold air even f the fan is running.

There are several common reasons why your AC compressor would stop working; they include:

Power issues

The first thing to check when your AC compressor is not working is the power supply to the AC. Next, check the power plug on the wall outlet and ensure it is secure.

If there is no power to the outlet, check for tripped breakers or a blown fuse in the breaker box. If the fuses and breakers are okay, you may have to call an HVAC expert.

Dirty coils and filters

Extreme buildup of dirt on the filters and coils can result in the appliance shutting down. Clogged filters reduce airflow such that the evaporator coil stops working. On the other hand, dirt condenser coils put excess pressure on the compressor, causing it to overheat.

Typically the compressor will automatically shut down to protect itself from getting damaged. Wash the coils and replace the air filters to improve air circulation in the AC.

Capacitor and starter relay problems

The capacitor supplies the power needed to start and run the compressor, blower motor, and outer fan. At the same time, the starter relay transmits power from the capacitors to the compressor.

Therefore, when the AC compressor is not working, either or both of these components could be the culprit. A significant sign of a faulty capacitor is a humming sound from the AC. Fortunately, you can easily replace both components.

Dead compressor

The AC compressor can fail due to a faulty capacitor or continuous overheating. The only solution here is to replace the compressor with the help of an HVAC expert.

Delonghi portable air conditioner exhaust fan is not working

The exhaust fan in a portable air conditioner vents the hot air from the appliance to the outside. If the AC’s exhaust fan is not working, the warm air will flow back into your room, negating the cool air entering the space. Here’s how you can troubleshoot the issue.

Power issues

First, listen to the humming sound of the compressor. If the exhaust fan is not working and there is no hum, the compressor isn’t receiving any power. This could be due to a circuit breaker issue. First, check if the power outlet is working; if not, go to the breaker and reset it if necessary.

Faulty contactor

If the circuit breaker has no issues and the compressor isn’t working, the contactor may be faulty. The contactor regulates the power flow to your AC compressor. To confirm this issue, check the contactor’s voltage. To fix this issue, you must contact an experienced HVAC professional.

Defective capacitor

The capacitor could be defective if the compressor is humming, but the exhaust fan isn’t spinning. Usually, the exhaust fan doesn’t require much power once it’s running, but it needs a big jolt of energy to start.

So the capacitor keeps this energy stored to use to start the fan. Therefore, if the capacitor breaks down, there will be no power to start the exhaust fan.

First, test if the capacitor is defective by manually trying to jump-start the fan. Turn on the AC, then use a long wooden stick and fit it through the fan grille. Use the stick to push the fan hard enough to give it a good spin.

Ideally, this should get the fan moving. If the fan starts, call an HVAC expert to replace your capacitor. If the fan doesn’t move, the problem is elsewhere.

Bad exhaust fan motor

A faulty exhaust fan motor is usually a result of a poorly maintained portable AC. The only solution for a bad exhaust fan motor is to replace it with the help of an HVAC expert.

Delonghi portable air conditioner buttons are not working

If your portable AC’s buttons stop working, try the following troubleshooting tips:

System error

If the buttons on your AC’s control panel stop working after a power interruption, try resetting your unit. A reset will clear any system glitches causing the control panel to act up. Turn off and unplug your AC for a few minutes, then restart it.

Loose wires

Loose wires inside the control panel could prevent the buttons from responding. If you suspect loose wires, try holding down the panel with one hand and pressing the unresponsive buttons with the other and see if it helps. If the affected buttons respond, you’ll need an expert to fix the wiring issues.

The user interface control board is faulty.

This is the board that houses the set of buttons you push, and it processes the settings you choose. So if the buttons fail, it’s likely the board is faulty. The best solution for this is t replace the control board.

The remote control is too far.

If your Delonghi AC remote control is not within the operational range, the buttons on the AC won’t work. Place the remote control within 33 feet of your unit.

Defective internal parts

The buttons on your portable AC send electric signals to the various components of the AC. Sometimes when the buttons fail, the issue could be with the main control board or other internal components.

For instance, if the fan buttons are faulty, you should probably check the fan first. Burnt-out evaporator coils can also cause unresponsive buttons. Diagnosing these issues may be quite complicated. Therefore you’ll need to call an expert to help identify the faulty part.

Delonghi portable air conditioner remote is not working

If your Delonghi portable AC is in working conditions, but it’s not responding to the remote control, follow the troubleshooting guide below.

Move closer to the unit.

The remote control must not be more than 7 meters away from the AC, without obstructions between the remote control and the receiver. Remove all obstacles such as furniture between you and the appliance interface.

Also, ensure the sensors on both the remote control and the unit are free from dirt and grime, preventing the signal from being received. Use a slightly damp cloth to clean the sensors.

Replace the batteries

They are probably dead if you haven’t changed the AC remote control batteries. To replace the batteries in your Delonghi AC remote control:

  • Take out the cover at the back of the remote control.
  • Insert two R03 ‘AAA’ 1.5V batteries inside the battery compartment. Make sure the polarity is correct.
  • Then replace the battery compartment cover.
  • Try testing the remote control. If that doesn’t work, there could be dirt or blockage between the batteries and the metal contacts.
  • Remove the cover, remove the batteries, and use a cotton swab dipped in isopropyl alcohol to clean the contacts.

Check the remote control LED light.

The LED light at the front of the AC remote control sends signals to the sensor on the unit’s interface. If you dropped the remote control, the LED indicator could disconnect from other internal components.

You will need an infrared sensor card to test if the remote control sends signals correctly from the LED. If not, you may have to replace the entire remote control.

Delonghi portable air conditioner not working as well after moving.

You should wait about 30 minutes before turning on your air conditioner after moving it so that the refrigerant can settle correctly. If you start operating the AC too soon, it can potentially damage itself.

For example, if you roughly handled your unit or carried it upside down, you will need to wait 24 hours before starting it. Fortunately, Delonghi portable ACs have internal safety mechanisms that protect the system from turning on if the refrigerant is disturbed.

Delonghi portable air conditioner is too noisy.

Ideally, Delonghi portable air conditioners are very quiet, with noise levels equivalent to a ceiling fan. The most quest Delonghi portable AC model is the DNC65, with a noise rating of 34 dB(A), thanks to its ceramic disc technology.

Unfortunately, there are several reasons why your portable air conditioner gets noisy. Common undesired noises from the portable AC are buzzing, humming, rattling, hissing, or banging.

Here are the most common reasons for a noisy AC and solutions to help your Delonghi portable AC get quieter.

Fan settings

The higher the speed settings, the louder the appliance. The maximum speed achieves the target temperature quickly, but it’s the loudest setting; medium speed reduces noise levels but maintains a good level of comfort, and the low speed is for silent operation.

Therefore, running the AC on a lower setting will reduce the noise and provide plenty of cooling.

Pulsating noise

A pulsating noise usually comes from a vibrating AV compressor because it is not securely fixed. If the compressor has little wiggle room, the forces that run it will move it from side to side, causing it to vibrate.

Alternatively, the refrigerant cables might also cause the portable AC to make loud pulsating noises. If the cables are too close, they will vibrate, hitting the wall and generating a pulsating sound.

To stop the AC compressor vibrations, access the compressor and check the platform it sits on; plastic platforms can crack easily, causing the compressor to pulsate. Instead, you can replace it with a wooden platform.

Whistling noise

Lack of airflow will cause a whistling sound from the portable conditioner. Your unit is probably working too hard to pull sufficient air from the room through its system.

Objects like furniture, windows, or walls could block the portable AC’s air intake, causing your unit to whistle.

The best solution to fix the whistling noise from your portable AC is to clean your air filters which will increase the airflow of the AC. Also, remove any obstacles around your AC unit that could limit airflow in and out of your AC.

Banging noise

A banging sound from your portable is a sign of a broken fan or compressor. It could be loose fasteners, an unstable unit, or a broken piston. It could also be dirt particles inside your appliance, which is an easy fix. You can turn off the appliance and use a vacuum to clean the inside of the unit.

Buzzing noise

A buzzing sound from your portable AC could be a sign of the following reasons:

  • A faulty connector or contactor switch
  • A bad capacitor
  • A worn compressor

Squealing sound

A defective fan blower motor could cause a squealing noise from your portable air conditioner. Unfortunately, this is a complicated and costly repair, so you must hire a professional technician.

Also, if you haven’t used your portable AC in a while, it may produce a squealing sound while it warms up before working properly again. Colder months also dry out your appliance’s lubricants.

Hissing noise

This sound indicates that the refrigerant that cools the warm air is leaking from the compressor, and you should switch it out before damaging the AC unit. The following things happen when the AC refrigerant is leaking:

  • First, it takes longer to cool the room.
  • Second, the vents blow warm air throughout.
  • Third, the AC wastes energy and leads to increased electricity bills.
  • Finally, the refrigerant line ices over.

If any of these happens to your Delonghi portable Ac, only a certified appliance can refill the refrigerant and check for leaks.

Clicking when the unit is on

When you hear a loud clicking sound every time you turn on your portable AC, it indicates the thermostat, control board, or capacitor is not working properly. If the noise persists before turning off the unit, it’s likely an issue with the compressor start relay.

Pulsing noise

A poorly insulated compressor in your portable AC could produce a loud or soft pulsating sound. Usually, the surface the compressor sits on will pulsate or buzz while the AC is running.

Delonghi portable air conditioner heater is not working

Delonghi makes some reverse-cycle air conditioner models that do both heat and cool. But sometimes, you might notice the heat output system is not working. Here are the common reasons that might explain this issue.

Clogged air filters

Dirty filters cause various problems, including no heat from your AC. Dirty filters reduce airflow. If insufficient air passes over the coils, the appliance won’t be able to warm up the air effectively. Worse case is the system may overheat because of the increased workload.

Ice buildup

A clogged filter In the AC can also cause the coils to freeze. The same will happen if the external temperatures are too low or if the refrigerant is leaking. Frozen coils won’t be able to exchange heat. Therefore, there will be no warm air production.

Incorrect temperature settings

You should always check if the thermostat settings are correct if you have an AC that can heat and cool like the Delonghi C3.5KW H3.4KW model. Also, some systems might not kick in until the indoor temperature falls significantly.

Defrost cycle

Your reverse-cycle portable AC can start the defrost cycle if the ice builds up outside the unit. The AC will quickly switch from heating to cooling because it has to blow warm air to the outdoor coils to thaw the ice.

Electrical issues

Check if the power outlet has tripped and fix it. If the outlet it okay, look for a tripped breaker or a blown fuse in your breaker box. Also, wiring issues in your portable AC will prevent the system from initiating the heating process. Check for corroded or disconnected wires.

Leaking refrigerant

The refrigerant is responsible for cooling and heating in a reverse-cycle air conditioner. If there is no adequate refrigerant flowing in the coils, the AC won’t effectively heat the air.

Delonghi portable air conditioner is not dehumidifying

During normal operation, the Delonghi portable air conditioners pull heat and moisture out of the air. The moisture from the air slowly accumulates on the evaporator coils, drips down into a drain pan, and drains via the condensate drain line. So if your AC isn’t dehumidifying in your home.

The thermostat fan is on.

First, check your thermostat. If your fan is on, it could prevent your portable AC from dehumidifying your room. Your AC fan should run only during cooling cycles, then shut off.

When the AC fan shuts off, all the moisture absorbed by the cooling coils has time to collect and drain. However, if the fan is blowing continuously, all that moisture sitting on the coils blows back to your home.

The solution is always to ensure your thermostat fan is set to AUTO and never ON.

Dirty evaporator coils

Evaporator coils are responsible for absorbing heat and moisture from the external air. But if they are too dirty, your AC will run longer and struggle to cool and dehumidify your home. You’ll have to clean the evaporator coils with a shop vac or coil cleaner.

Leaking refrigerant

The refrigerant in your AC moves heat and moisture out of the external air and drains it outside. But if the refrigerant lines develop leaks, your AC becomes less cooling and dehumidifying.

Leaky ductwork

Almost all your home’s ductwork(pipes, vents, and tubes) is leaky to some extent. Unfortunately, leaking ducts in your basement, attic, or crawl spaces pull humid, dirty air into your home.

This means your portable AC’s dehumidifying power will be futile. The only way to fix this is to have a professional inspect your home’s ductwork and fix any leaks.

Your portable AC is oversized.

You will notice high indoor humidity levels if your AC is too big for your home. When an AC system is too big for the desired space, it cools the area too quickly, shuts off then switches back after a short period.

This “on-then-off-again” process is called short-cycling. Short-cycling prevents the AC from dehumidifying your room because dehumidification works best when the AC runs longer, steadier cooling cycles.

Consult an HVAC expert if your appliance is too big for your home and consider replacing it with a smaller unit.


Portable air conditioners are an essential appliance in the summer. But if you have issues, you can easily fix them using our troubleshooting guide. Before going for repairs, always ensure your Delonghi portable AC settings are correct to make the most out of your AC.

Similar to other electrical appliances, always observe caution when trying to repair your Delonghi AC.