9 Reasons Your Portable AC Keeps Shutting Off (+ Fixes)

After you have set a portable air conditioner in your room you want an uninterrupted autonomous cooling operation by it. The goal is to comfortably perform your work in the day and get a good night sleep with the AC doing its job. It could be real annoyance if your portable AC keeps turning off after short intervals.

Repeated shutting off of a portable AC is called short cycling. There are various reasons for your portable AC compressor to turn OFF frequently including dirty filter, clogged condenser, leaking refrigerant or a faulty compressor. Timer or inadequately set or faulty thermostat could also lead to consistent turning ON and OFF of portable AC.

There are problems like dirty filters and condensers that you can fix yourself by following the solutions suggested. However some of the reasons for short cycling are complicated and dangerous to resolve by yourself. However it could be a great time and money saver if you know the problem beforehand.

Why Your Portable AC Keeps Shutting Off?

There are several reasons to why your portable AC could be short cycling. The most probable causes of your portable AC turning off and on are discussed below with solutions. Best is that you diagnose from the most obvious and easiest.

1. Dirty Filter

The air that is delivered by the portable AC after passing through evaporator coils is cleaned by passing through air filter. With time the filter is blocked by dust and debris and requires maintenance.

Filter has to be cleaned after specific hours of cooling operation. This time depends on the quality of the air that passes through it i.e. dust and particles in it.

If the filter is not cleaned after it becomes dirty it will restrict the air flow through it. As a result the flow rate of the air would be reduced compared to recommended flow. In order to compensate for this loss the compressor will have to work harder. As a result system may overheat and result in turning off before the cycle is complete. If this happens continuously for a sufficiently long interval of time it can lead to permanent failure of the compressor.

In fact the restriction of air flow due to filter can cause other inconveniences specifically in portable ACs like filling up with water very quickly. This happens due to lack of airflow in through the evaporator coils and as a result moisture will freeze up and drip in the condensate pan.

As this is the regular maintenance process portable AC manufacturer make it very easy in their units for the filter to be extracted, conveniently cleaned and refitted. Usually there are no screws and and filter can be extracted very easily.

Most of the air conditioners have filter reset indicator. It turns on when the filter is dirty or specific number of hours have been passed in the operation. The duration after which the filter reset light turns on is assigned by the company. The air conditioner will not turn ON until you take out the filter, clean it and then put it back on.

So give a check to air filter of your portable AC. Extract the filter out and clean it. The filters in air conditioners are almost always reusable so you will not have to change it. Use lukewarm water to wash the air filter gently. Allow it to dry properly before inserting it back.

2. Blockage of Airflow

Your portable AC requires adequate airflow to and from the room. When the airflow is insufficient it results in overworking of the compressor to compensate for the air loss. As a result your unit’s compressor will overheat and eventually turn off. It will not turn on until compressor temperature drops.

Another problem that may arise due to the obstruction of airflow is freezing of the evaporator coils. Evaporator coils need specific airflow rate. If the airflow rate reduces than the set limit then it will drop the temperature of the coils below the adequate temperature. The coils will become too cool and freeze up.

Besides moisture buildup and hindering of airflow another demerit of the coils freezing up is that the ice will keep melting. Water will continuously drip in the condensate pan and it will fill up way quickly.

The solution is easy just keep some space around your portable AC. The airflow from the unit to the room and vice versa must not be prohibited in any way. Plants, furniture, decoration pieces or any hindering material should be at sufficient space from your unit.

Also check the vent hose from inside for any hindrance or solid objects. Especially make sure that the open end of hose is not blocked by anything outside the window or hole.

3. Lack of Refrigerant

Portable air conditioners cool by using vapor compression cycle. To be simply put they operate on a closed cycle. This means that the refrigerant that is flowing with in the lines is not used up. In fact it is just interconverting between liquid and gaseous state to perform the cooling operation.

Hence the quantity of the refrigerant in the portable AC is supposed to stay the same irrespective of the hours of operation. It is not a maintenance process. Thereby if there is a reduction in overall pressure in refrigeration lines it is due to leakage anywhere in the lines.

In case your refrigerant is leaking it will result in short cycling of your portable AC. The reason is inadequate pressure levels in the refrigeration line.

Due to low refrigerant quantity the refrigerant pressure will become low to the extent that compressor will turn off before the completion of cooling cycle. When the pressure becomes high again the compressor turns back on. This repeated turning on and off results in high power consumption and reduction of the portable AC life due to wear and tear.

This means that if you have low refrigerant in your portable air conditioner it is probably due to leakage. Before charging the portable AC you will have to detect the leakage. It may or may not be easy to find. If your portable AC got a hit someplace or you see a bend there it is very likely that there is leak in the same area.

After detecting and fixing the leak slowly introduce refrigerant in small quantities to the suction line. Make sure that you are using the same refrigerant that is compatible with your portable AC. Give time between addition to stabilize the system. You can check out a detailed guide to charging your air conditioner.

Recharging your portable AC is not a very straightforward process and requires experience. If it is your first time and you have not done it before I recommend that you call an HVAC professional technician to do this for you. Technician will detect the leak, patch it and recharge it for you. It will also save you a lot of time.

4. Clogged Condenser Coils

If you have blocked condenser coils flow of air through them will be restricted. As a result your air conditioner will have to work harder. This may result in overheating the condenser to the extent that it turns off. Extensive variation in temperature will cause the unit to short cycle.

Not every portable AC will give you access to the condenser coils. But in case it does you may clean them by using a soft brush. Clean the condenser coils with gentle upward and downward motion. Get rid of debris and dirt.

Clean carefully as the condenser coils are very fragile. In case you physically affect the condenser coils performance of portable AC will be compromised. The refrigerant may leak out and the only solution may be to change the condenser coils.

You should clean the condenser coils at least once a year to keep the performance of your portable AC intact and maintain its life. Do this early and you will save yourself a lot of money and effort.

Also try to keep plants and foliage away from the portable AC. Keep them away from the intake hose in case of dual hose portable air conditioner to prevent getting your condenser coils clogged. In case condenser coils are not easily accessible you may vacuum through the holes on top of the housing of condenser coils.

5. Inadequate Cooling Capacity

Another reason for short cycling could be operating an air conditioner that has way higher capacity than the size of the room.

When a high capacity AC is operated in a relatively small room then we expect that it would cool better. However in fact it will have low efficiency and poor quality of air conditioning. It will cool the room very quickly and turn off after running for a very short time. This will result in more energy consumption than running of an smaller AC for longer period of time. Repeated turning on and off creates added strain on your system.

Another demerit is undermining the secondary function of your AC i.e. removing humidity. When the air conditioner is of capacity relatively higher compared to the room it will not remove water effectively from air.

This is more probable to happen in an split AC system. It is unlikely that a portable AC that has cooling effectiveness way less than equivalent split or central AC can short cycle due to large capacity. However it is possible if the room is way smaller than the cooling capacity of your portable AC.

6. Faulty Compressor Unit

Compressor is the most important component of any air conditioner operating on vapor compression cycle. It is in fact the only necessary moving component in the air conditioning cycle. Compressor pressurizes refrigerant that is later on expanded to get the cooling effect that cools your home.

Another reason that is rare but may lead to short cycling of the unit is malfunctioning compressor unit. If there is buildup in the compressor that is obstructing the flow of refrigerant, compressor will overheat and shut down. It will turn back on when it cools down. The process will repeat itself resulting in the unit that keeps shutting off due to dirt and grime within compressor unit.

It is usually uncommon that the reason for overheating the compressor is within the compressor itself. However it could happen. If that is the case there are two options: Replace or Repair. In either case call a certified AC technician to resolve this problem for you.

Compressor is the most expensive component of the air conditioner to replace or repair. So before making the decision decide whether it is cost effective when your current portable AC value is taken into account. Usually it is better to buy a new unit.

7. Wrong Settings in Control Panel

Filter Reset Panel (Kenmore Elite)
Filter Reset Panel (Kenmore Elite)

Before diagnosing any other problems in your portable AC it is a good idea to give your control panel a check. Just to make sure that the right settings are selected and it is not the actual cause of the unit turning on and off.

Check the timer if your portable AC has one and disable it if it is on. If your AC turns off exactly after the same interval of time, it could probably be due to timer.

Also make sure you have not selected a temperature on your thermostat that is close to ambient (surrounding) temperature. This may continuously switch your portable AC on and off after short intervals. It will turn off very quickly after the set temperature is achieved and then turn back on with slight deflection in temperature. If the ambient temperature is below selected temperature your AC will seize the cooling process.

8. Frozen Evaporator Coils

If the condensed water on cooling coils is not drained it can result in formation of frost on them. This draining is consistently carried out by the adequate airflow through the coils. If something is hampering the airflow then this would lead temperature of the coils low to the extent that condensed water would convert to ice. The result is hampering of airflow and thereby overworking of the compressor.

There are several reasons why ice can be formed on evaporator coils of your portable AC. One of the common reasons is dirty filter that blocks the airflow resulting in freezing of coils. Cleaning and maintenance should be carried out routinely to avoid this. The diagnosis of the dirty filter is discussed previously in the article.

The other common cause could be a malfunctioning fan. It the fan is not operating at adequate speed then the flow rate of the air required would decrease resulting in freezing of the coils. Same happens in case there is obstruction of airflow by anything that is in the path of air that is delivered. There are other causes leading to frozen evaporator coils that are less probable but possible.

As I mentioned previously that portable AC is not like automotive AC. It needs not to be recharged thereby, ever. The quantity of refrigerant is supposed to remain the same. However if there is a leak then refrigerant pressure would drop absorbing more heat and freezing of coils.

A malfunctioning thermostat can sense incorrect ambient temperature overworking even after the desired temperature is achieved and eventually resulting in frozen AC coils.

9. Malfunctioning Electronic Components or Electrical Wiring Problems

Consistent turning on and off, especially if the portable AC turns on and then off right away could be due to electrical problems. There can be majorly two problems; either electrical wiring is partially burnt from someplace or you have a faulty electronic equipment like capacitor or relay.

Give a check to your electrical wiring. Just trace the each wire to make sure it looks okay. Check if the connectors are not loose. Usually intermittent turning on and off is due to capacitor as it performs the role of continuous power to compressor. In most cases if capacitor is damaged you will see it bulged on top. It is highly uncertain that despite the bulged body of capacitor it is working fine.

Another electrical problem could be a faulty relay. If you have a faulty relay then your compressor will not turn on from the beginning. Relay performs the role of a switch and usually has four pins. Temperature sensors that power HVAC units require levels of amperage that vastly exceed the capacity of their wiring. Relays provide the necessary amplification to convert a small current into a larger one.

Electronic components are usually conveniently available for cheap. Although it is a simple soldering process to install the capacitor or relay I highly recommend that if you do not have familiarity with the similar kind of work call a professional technician to replace it for you.

Replacement of Relay

The video below is for diagnosis and replacement of capacitor in central air conditioning however procedure is the same in portable AC. Just make sure that you buy the relay or capacitor of the same specification required for your model.

Replacement of Capacitor