8 possible reasons behind AC not cooling properly

Air conditioner not cooling

What you least want on a hot summer day is an air conditioner that can’t cool. There can be several reasons behind AC not cooling problem, some of which are technical faults and some are non- technical.

Most common reasons behind AC not cooling are:

Clogged air filter

If the air conditioner does not cool, the air filter might be clogged. In such case, air cannot flow through properly which greatly reduces the cooling capacity of the air conditioner. Either clean the air filter or replace it as needed.

Dirty coils

If the air conditioner is not cold enough the condenser coils may be dirty and loaded with debris. In an AC, the condenser is like a radiator that dissipates heat (which was removed from the air). The condenser coil must be clean to dissipate heat outside. As the coils get dirtier the air conditioner becomes less efficient, which makes it work harder to cool the room. If the coils are dirty enough, the unit will never be cold enough and will not be able to cool the room.

Insufficient coolant

The coolant circulates through the evaporator coils and cools the air flowing over it and eventually sends cool air into the room. So when the level of this coolant becomes insufficient, the AC fails to cool. At this stage call a PRO for coolant top up and refill.

Faulty compressor

A compressor is the heart of an air conditioning unit which is responsible for cooling your room. If the air conditioner does not cool, the compressor might be defective. The compressor is a motor which compresses the refrigerant or coolant and circulates the refrigerant through the evaporator and condenser coils. If the compressor goes bad the cooling cycle does not start and the AC fails to cool.

READ ALSO:  Why has ice formed on my air conditioner?

Faulty thermostat

A thermostat is a sensor that senses the room temperature and hints the compressor to start or stop the cooling cycle. If the thermostat is defective the air conditioner does not cool or may cool continuously.

Defective parts

The other possible technical reasons behind AC not cooling can be a faulty run capacitor of the compressor, defective control board, bad thermistor, choked capillary, faulty motor etc.

High atmospheric temperature

An AC has an optimum operating temperature (surrounding temperature) at which it can work most effectively. If the temperature shoots up beyond the optimum temperature limit, the efficiency of the air conditioner goes down. Sometime it is so hot outside that a stage is reached where the compressor stops working completely.

Undersized AC

A common mistake people make is that they buy an AC based on their budget and not based on the requirement of the room. A small AC in a huge room will always find hard to cool the room in peak summers. The size of the AC should be according to the size of the room.

Faulty AC Remote

There can also be a situation when the remote fails to send temperature change signals to AC unit. A simple replacement of remote will do the trick. Here, are a few Brand specific AC remotes and a universal remote that you can get on Amazon via reputed sellers:


So if your AC is not cooling, book a case with Mr Right.

For more information on AC care and maintenance refer to Ideas by Mr Right





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    Hi Mr right,I just bought a window ac,though the compressor is working perfectly fine,if I stand directly to the ac I feel the coolness of it,but it doesn’t circulate my room properly,1$half inches is Wat I bought.what could be the problem..the thermostat is on testrun

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    Sir good day. My split type ac is not cooling when i start switch on the ac are running ang blown air not cool din the condenser fan motor is running but after how many minutes is automatically stop the fan motor of condenser..and not running again so i switch off and on the ac again. My question is what problem of my ac condenser

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    Thanks for pointing out that has the condenser coils in an AC unit get dirtier the air conditioner becomes less efficient which makes it harder to cool the room. My husband and I recently noticed that our house doesn’t seem to be cooling properly, and since we don’t think the refrigerant is leaking or anything we’ll have to look and make sure that the coils are clean. It’s been especially dusty lately which, so it would make sense. Either way, I think we might just have to buy a new one soon since this one has been having a lot of trouble lately.

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    My Mitsubishi ac cooling problem. I changed composer and capacitor.capillary &indor fan motor& make flash with 141 gas & service cooling coil but still not cooling. Thermostat is ok becoz composers is working no stop. What next I do for the cooling???

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    Voltas 5 star 1.5 ton window ac 2016 model not properly colling and after 30 sec of cooling gets autocut and spread normal air, also water is not coming out from this whole season. If coils are getting dirty how can service it.

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    Not ac properly colling and after 30 sec of cooling gets autocut and spread normal air, also water is not coming out from this whole season. If coils are getting dirty how can service it.

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    Indoor has been changed to 2.0 lit in split AC….outdoor unit is of 1.2 lits by Mechanic while Repairing.
    Now cooling is Nil.
    What to do…..???

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    My one day old ac is not cooling….. last night it was cooling very well bt right nw there is no cooling,even the voltage is showing zero

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    Thankyou so much, now I exactly knows the causes and reasons why my Air Conditioner not cooling, this explanation gives me more to understand my trade,,,,

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