Maintenance and service of air conditioning – what to do regularly and what to leave to professionals
Air Conditioner Maintenance and Service – What to Do Regularly and What to Leave to a Professional
Air conditioning units are now a common household and commercial appliance. Most people turn them on in spring, rely on them all summer, and forget about them by the end of September – until the next time they switch them on and a cloud of dust comes out of the unit, or it stops cooling. In fact, proper and regular air conditioner maintenance is not complicated, doesn’t take long, and most importantly – significantly extends the lifespan of the device, saves electricity, and maintains indoor air quality.
In this article, we will comprehensively cover the entire topic of air conditioner service and maintenance. We will distinguish what a regular user can do themselves, what requires a service technician, what are the recommended intervals, what problems arise from neglect, and how to take care of the outdoor unit throughout the year. We will focus mainly on split and multi-split systems, which are the most widely used in practice.
Why air conditioner maintenance is so important
An air conditioning system is a thermal machine that works with refrigerant, a compressor, heat exchangers, an electric motor, and electronics. Each of these components has its own requirements for cleanliness and operating conditions. For example, if the evaporator (indoor unit) is clogged with dust, air flows through it more difficultly – the fan has to work harder, the compressor is overburdened, and electricity consumption increases. Studies from real-world practice show that a neglected air conditioner with a dirty filter and clogged heat exchanger can consume 20 to 35 % more electricity than an equally powerful but regularly serviced unit.
From the perspective of air quality, this is an even more serious problem. Filters and evaporator fins are a humid environment – an ideal place for bacteria, mold, and mites to multiply. The user then wonders why their head hurts or they have allergic reactions from the air conditioner. The answer is simple: they are breathing air that has passed through a microbial hotspot. This can be prevented by regular cleaning and, if necessary, disinfection.
Finally, the costs of repairing a broken air conditioner are always higher than the costs of regular preventive maintenance. Replacing a compressor, for example, costs dozens of percent of the price of a new unit. In fact, most compressor failures occur precisely due to poor cooling caused by clogged heat exchangers.
What the user can do themselves – regular home maintenance
Let’s divide the care of an air conditioner into two levels: what belongs to the hands of a regular user and what requires a service technician. We will start with the first – and this is also the largest part that determines the daily quality of operation.
Cleaning the air filters in the indoor unit
This is undoubtedly the most important task you can do yourself. The air filter in the indoor unit (wall unit) captures dust, fibers, pollen, and other solid particles. It is the first line of defense for the entire heat exchanger. If the filter is dirty, air stops flowing sufficiently and the evaporator starts to "freeze" – a layer of ice forms on it, which can damage the air conditioner.
Recommended interval: every 2 to 4 weeks during active operation, in dusty environments (workshops, kitchens, facilities with animals) even every 10 to 14 days. In a household with a less dusty environment and not daily operation, once a month may be sufficient.
Cleaning procedure: Turn off the air conditioner. Open the cover of the indoor unit – it usually flips up or pulls forward, depending on the model. Remove the filters. Gently shake them off, then rinse them with warm water. If they are greasy (kitchen), use a mild soap solution. Let them dry completely in the air – never dry them with a hairdryer or put them back wet. Return the clean filter to its place and close the cover.
Visual inspection of the outdoor unit
The outdoor unit (condenser) is outside all year round. Every month, it is worth at least visually checking the following:
- Whether the grille or condenser is clogged with leaves, seeds, spider webs, or insects
- Whether there is visible mechanical damage to the unit (bent fins, cracked plastic)
- Whether the unit emits an unusual sound during operation (squeaking, knocking)
- Whether there is any object near the unit that blocks the air intake or exhaust
- Whether there is a frosty coating on the thick copper pipe (during cooling – a sign of a problem)
You can carefully rinse the condenser (outer fins) with a garden hose at a gentle pressure – from front to inside, i.e., in the direction the air normally flows. Never do this while the unit is running and be careful not to let water flow into the electrical terminal box. If you are unsure, it is better to leave it to a technician.
If you have an air conditioner from the IVAR.2.0 range, there are also special accessories available for the outdoor unit – for example, RAIN PROTECTION KIT for IVAR.2.0 air conditioners, which protects the condenser unit from heavy rainfall and extends the life of electrical components, or INSECT PROTECTION KIT for IVAR.2.0 air conditioners, which prevents insects from settling in the unit – which is a serious problem in practice, as insects (especially ants and cockroaches) can cause short circuits in the control electronics. More about protecting the outdoor unit from rain and insects can also be found in the article Protecting the outdoor unit from rain and insects – why and how to do it.
Condensate drain inspection
The indoor unit condenses moisture from the air during cooling – producing water. This water drains out through a drain hose. This hose can become clogged (limescale, biological coating, insects). The result is water leaking from the indoor unit into the room – one of the most common complaints that service technicians address.
Every month during the cooling season, check whether water is dripping from the drain outlet outside during air conditioner operation. If nothing drips during long cooling periods, the drain is likely blocked. You can try cleaning it yourself – by gently flushing through the accessible end of the hose or blowing air through it. If you are unsure where the hose leads, leave it to a technician.
Cleaning of louvers and indoor unit cover
Outlet louvers (air direction) and the outer plastic of the unit collect dust and dirt. You can easily wipe them with a damp cloth and mild cleaning agent. Never use aggressive chemicals – they may crack the plastic. Do this approximately once a month or as needed.
If you need to replace or repair the cover of the outdoor unit, for IVAR.2.0 air conditioners, for example, the Bottom cover for IVAR.2.0 or the variant Bottom cover – IVAR.2.0 9HP MINI is available. These are replacement parts that help in the case of physical damage to the cover without the need to replace the entire unit.
Regular switching on outside the main season
The air conditioner should not remain unused throughout the winter without any activity. It is recommended to switch it on at least once a month for 15–20 minutes in heating mode (heat pump) or fan mode. This helps maintain the compressor lubrication and prevents jamming of moving parts. Modern inverter air conditioners can heat even in winter (most up to –15 °C outdoor temperature), so they can be operated year-round.
What belongs exclusively to the hands of a professional – professional service
There is an entire area of service work that a layperson simply cannot perform safely. Either due to safety reasons (work with electricity, refrigerant), or due to technical complexity (settings, diagnostics, measurements).
Checking and refilling refrigerant
Refrigerant is the working substance that enables the entire cooling cycle. If the system does not leak, refrigerant escapes and the air conditioner cools worse and worse until it stops completely. Measuring refrigerant pressure and its possible refill require special manifold gauges, knowledge of the specific type of refrigerant (R32, R410A, R290, etc.) and in many countries also a certificate (F-gas certificate). In Slovakia, work with refrigerants can only be performed by certified technicians. Layperson handling of refrigerant is not only dangerous, but also legally punishable.
Signs of refrigerant leak: the air conditioner cools slowly or not at all, the outdoor unit makes unusual sounds, oil deposits or frost appear on the piping in the wrong place.
Cleaning of the evaporator and condenser with high-pressure water or chemically
The fins of the evaporator and condenser are very fine and tightly stacked. Dust, grease and biological growths get trapped between them and no household cleaning agent can remove them without the risk of damage. Service technicians use special alkaline or acidic cleaning foams that are chemically compatible with aluminum fins. After application, the fins are rinsed with a high-pressure water jet. The wrong chemicals or incorrect water pressure can bend the fins and permanently reduce the device's performance.
This cleaning is recommended once a year before the season (spring) and twice a year in case of intensive operation (restaurants, production, hotels). Professional technicians also disinfect the drain pan and drain hose at the same time.
Measuring electrical quantities and checking components
During the professional inspection, the technician measures the power and current values of the compressor and fans, checks the capacitors on the fan motor (commonly worn), inspects the terminal block and electrical connections, verifies the correct operation of the control electronics and possibly reads error codes from the memory of the control unit. These tasks require professional equipment and electrical qualifications.
Disinfection and biological sanitation
If an unpleasant odor is coming from the air conditioning or mold growth is found on the evaporator, a deep biological disinfection is necessary. The technician applies a special biocidal product that destroys bacteria and mold. This product must not remain in the system and must be thoroughly rinsed afterwards. Domestic disinfection with sprays from the store is only superficial and does not solve anything in the case of real biological contamination.
Checking the tightening of connections and mechanical inspection
Vibrations during operation gradually loosen screws, terminals and pipe connections. At least once a year, it is advisable to mechanically check whether all connection points are tightened, whether the thermal insulation on the supply pipe is not cracked or peeling off (which causes condensation on the pipe and increases heat losses).
Recommended service plan – overview of intervals
| Task | Who performs | Interval |
|---|---|---|
| Cleaning of air filters | User | every 2–4 weeks (season) |
| Visual inspection of the outdoor unit | User | monthly |
| Condensate drain check | User | monthly (season) |
| Starting outside of the season | User | once a month (outside of the season) |
| Chemical cleaning of heat exchangers | Service technician | 1× a year (before the season) |
| Refrigerant pressure check | Service technician | 1× a year or in case of suspected leak |
| Electrical inspection and measurement | Service technician | 1–2× a year |
| Disinfection and biological sanitation | Service technician | as needed, min. 1× every 2 years |
| Checking pipe connections and insulation | Service technician | 1× a year |
Winter preparation and air conditioning preservation
If you do not use the air conditioning at all during the winter period (e.g. you only cool in the summer), we recommend doing a few simple steps before shutting it down. Run the air conditioning in fan mode without cooling for 30 minutes – the evaporator will dry out and not retain moisture that promotes mold growth. Clean the filters and let them dry outside. Visually check for any visible damage. Disconnect the remote control from the power supply (change the batteries and store them separately). You can cover the outdoor unit with a cover, but leave the sides ventilated – otherwise moisture is trapped under the cover and electrical components rot.
In the spring, when you start the air conditioning again, do a few minutes of test operation without full power and watch for any unusual sounds or odors. If so, contact service before you load the system to maximum on the first hot day.
Most common mistakes in "DIY service" and their consequences
From practice, we know several typical situations where DIY maintenance turns into a problem. I would mention at least four of them:
1. Cleaning the filter in the wrong way: People sometimes clean filters with a vacuum cleaner with a rigid attachment or rinse them under high pressure. The filter mesh is delicate and cracks. Once torn, the filter no longer performs its function and dust falls directly onto the evaporator.
2. Rinsing the condenser with a high-pressure cleaner: A Kärcher with full pressure and an unsuitable nozzle can bend entire rows of aluminum fins in the condenser within a few seconds. The result is a sharp drop in performance and an unnecessarily expensive repair.
3. Refilling "air conditioning gas" from a canister without measuring pressure: There are various refilling kits for laymen on the market. Without measuring the current pressure in the circuit, you risk overfilling the system, which is just as harmful as underfilling – and with modern R32, there is also a risk of flammability with unprofessional handling.
4. Applying disinfectants in a closed room: Aerosol preparations for air conditioning disinfection are often flammable and can be harmful to health when inhaled in large quantities. The room must be ventilated, and the air conditioning may only be started after complete ventilation.
Service and warranty conditions – what to pay attention to
Most manufacturers of air conditioners condition the validity of the warranty on regular professional servicing. The specific conditions vary, but generally applies: if a compressor failure occurs during the warranty period and the service technician finds that the condenser was grossly neglected (dust accumulated in centimeters), the manufacturer or seller may reject the warranty claim. Therefore, we recommend keeping records of service inspections – invoices or service reports. For professional systems (more on this in the article Air conditioning in professional heating – combination with heat pump and heating), it is even more important, as these are larger investments.
Service contracts with an authorized technician are standard for businesses (offices, shops, restaurants) and are cheaper in the long run than solving problems on an ad hoc basis. The technician comes twice a year, performs a full inspection, issues a report, and you have the certainty that the system will work without surprises.
Practical examples from customer practice
Example 1 – residential air conditioning, 5 years of operation without cleaning the evaporator: The customer complained that the air conditioner was cooling poorly and smelled when turned on. After opening the indoor unit, we found black biological growth covering the entire evaporator. The filter was cleaned, but the blades behind it were never. Result: complete chemical sanitation lasting 3 hours, costs 3× higher than a regular annual service. The air conditioner eventually achieved normal performance – it was lucky that the compressor lasted.
Example 2 – office multisplit, clogged drain: In the office, they noticed that the indoor unit was dripping water on the ceiling. The problem was simple: the drain hose was clogged with a mucus-like coating. Cleaning took 20 minutes, costs minimal. Unfortunately, the damage to the drywall ceiling cost several times more. Lesson: regular drain inspection is a cheap prevention against expensive construction repairs.
Example 3 – outdoor unit clogged with poplar fluff: The customer had the air conditioner installed near poplar trees. The condenser was completely clogged with white fluff. The air conditioner was running, but with enormous energy consumption and the compressor overheated. After cleaning the condenser, the consumption dropped by 28%. Recommendation: in areas with poplar fluff, inspect the outdoor unit every week during the flowering season.
Example 4 – malfunction after "self-refilling of gas": The customer bought a refill kit at home and "refilled" the refrigerant because the air conditioner was cooling poorly. A month later, he called saying the air conditioner was not working at all. Measurement showed a significant overfill of refrigerant – the pressure was 40% above normal. The compressor was operating under extreme conditions and eventually failed. Replacing the compressor cost more than half the price of a new unit. Conclusion: never refill refrigerant without a pressure gauge.
Special situation: air conditioning in combination with heating
More and more installations operate in the mode of an air-to-air heat pump throughout the year – cooling in summer and heating in winter. This significantly increases operating hours and thus also service requirements. For such year-round operation, we recommend:
- Cleaning filters every 2 weeks throughout the entire year (not just in summer)
- Professional service twice a year – in spring and autumn
- Checking the outdoor unit's defrost function during the winter period
- Ensuring that the condensate drain is protected against freezing (thermal insulation of the drain hose)
More on the combination of air conditioning with heating can be found in the article Air conditioning in professional heating – combination with heat pump and heating.
Accessories for longer lifespan of the outdoor unit
The outdoor unit is exposed to all weather influences. Intensive rain, snow, UV radiation, insects, and mechanical impacts (pebbles from a lawnmower, sports in the garden) – all of this is everyday reality. Therefore, it is not unreasonable to address protection proactively.
For IVAR.2.0 air conditioners, we recommend a combination of two accessories: RAIN PROTECTION KIT for IVAR.2.0 protects the upper part of the outdoor unit from direct water ingress into electrical components and at the same time reduces the corrosive effect on the condenser blades. INSECT PROTECTION KIT for IVAR.2.0 covers the openings through which ants, cockroaches or other insects would otherwise get into the area of the control board. A short circuit caused by insects is one of the surprisingly common faults, especially in the warmer areas of Slovakia and near greenery.
An overview of all available spare parts and accessories can be found in a separate article Accessories for IVAR.2.0 air conditioners – overview of parts and their function.
Signs that indicate the need for immediate service
Certain signs require immediate action by a professional. Never ignore them and turn off the air conditioner immediately if you notice:
- A strong electrical smell or burning smell – may indicate a short circuit in the motor or control electronics
- Sparks or smoke from any part of the system
- Loud knocking or grinding during operation – a signal of mechanical failure of the compressor or fan
- Ice on the supply pipe in indoor areas – may indicate a refrigerant leak or a serious flow problem
- Condensate drainage stops during prolonged cooling operation – risk of overflow into electrical components
- Defective defrosting of the outdoor unit in winter – risk of compressor failure due to operation in extreme conditions
For more information on identifying faults, see the article Common air conditioner faults and how to recognize them.
Frequently Asked Questions (FAQ)
How often should I clean the filters in my air conditioner?
It depends on the intensity of use and the dustiness of the environment. A general recommendation is every 2 to 4 weeks during the active season. In dusty environments (workshops, kitchens, homes with pets), even every 10 days. In a typical household with less intensive use, once a month may be sufficient. Never leave filters uncleaned for more than 6 weeks during operation.
Can I clean the outdoor unit myself with a garden hose?
Yes, but with important limitations: the air conditioner must be turned off and disconnected from the power supply. Spray water gently from the front through the grille, never from the side or from above. Never use a pressure washer – it can bend the delicate aluminum fins of the condenser and permanently reduce the unit's performance. If you are unsure, it is better to leave the condenser cleaning to a technician.
What is the difference between warranty service and post-warranty service?
Warranty service addresses faults caused by product or material defects during the warranty period (usually 2 years, 5 years with registration for some manufacturers). Maintaining the warranty typically requires professional installation and regular professional maintenance. Post-warranty service deals with repairs and inspections after the warranty period has expired. Both types of service must be performed by certified technicians when working with refrigerants or electrical installations.
Is it normal for water to drip from the outdoor unit during cooling?
Yes, this is a normal occurrence. Condensation of moisture during the cooling cycle produces water, which drains from the indoor unit through a drain hose. On the outdoor side, this water usually drips near the outdoor unit or directly from it (depending on the specific installation). A problem arises if water drips from the indoor unit into the room – this indicates a clogged drain or another issue.
Do I need to service my air conditioner if it is working without problems?
Yes, even an apparently trouble-free air conditioner should be serviced preventively. Many problems (biological growth, slowly leaking refrigerant, an impending fan condenser failure) manifest late – only when they cause more expensive damage. Regular service is economically more advantageous than reactive repairs and is also a condition for warranty validity for most manufacturers.
What should I do if I notice an unpleasant smell coming from the air conditioner when it is turned on?
Smells when turning on the unit can have various causes: a dirty or microbially colonized filter (solution: immediate cleaning or filter replacement), biological growth on the evaporator (solution: professional disinfection), a dried-out trap in the drain tray, or cigarette or other odors trapped in the filters. In the case of recurring or strong odors, contact a technician, as biological growth on the evaporator is a health risk and cannot be removed by home cleaning.
Conclusion – investment in maintenance always pays off
An air conditioner is a device that, with proper care, can easily last 15 to 20 years without major problems. On the other hand, a neglected unit can fail after 5–7 years, often in components that are expensive to repair. The difference is not in the quality of the device, but in the user's approach and the regularity of maintenance.
Responsibility is clearly divided: filter cleaning, visual inspection, and basic care are the responsibility of every regular user and take only a few minutes per month. Everything else – refrigerant, electrical work, deep cleaning of fins, disinfection, and diagnostics – belongs to the hands of a certified technician with the appropriate equipment. Respect this division and your air conditioner will repay you with reliable operation, energy savings, and clean air in the room for many years.
If you are considering the installation of a new air conditioner or need to choose a system for a specific space, we recommend reading related articles from our Knowledge Center – for example, How to choose an air conditioner for professional use – what to focus on, What air conditioner capacity do I need – calculation based on area and room type, or Installation of an air conditioner step by step – procedure and installation requirements.
Do you have a question about this topic?
Not sure or dealing with a specific situation in your home? Write to us – we are happy to help.