Weekend DIY - Keeping your Air Conditioning System cool

Hi there...it's Saturday, a nice day for some DIY.

This week I want to share some household maintenance tips on how to keep your Air conditioner (A/C) running cool. Of course, you may leave this to professionals and spend Php300-500 (about $10) but aside from the savings, this is kind of fun and you might learn something new. The only challenge here is you have to move quite a lot of muscle since an A/C unit is heavy. I have two 0.6Hp window type A/C and this weighs around 25 to 30 kilos. You have to lift that weight depending on how the unit is installed (height considerations). I can do this alone but of course, you can always ask for help. If you can manage this part, then the rest is easy and fun.

Read on, you might learn something...


About a week ago, I noticed that even if the A/C is on, the room is not getting cool like it use to be. Even if the front  panel indicates a good 20°C temperature, the room is quite warm. As I investigate, I noticed that the A/C unit is not blowing that much cold air, almost nothing, hence the warm room. Investigating further, as I remove the front panel and filter, there is a solid block of ice in the front aluminum grill. This explains the very little air blowing out since the ice blocks the flow of air. Also explains why the display indicates a cold temperature even if the room is still warm, the sensor is touching the ice buildup causing a false temperature reading.

At this point, I know what has to be done. You see, an A/C unit freezing up means the cooling system is out of balance and heat exchange is not being done properly. And the primary cause, dirt buildup on the condenser and evaporator units. Having mentioned these parts, and to have a good appreciation of how important it is to keep your A/C unit clean - I'll briefly explain the basic principle of how the A/C changes the ambient temperature of an enclosed space like your room (take note, it must be an enclosed space).

Scientifically speaking, it does not cool the room by just simply blowing cold air inside the room. As I've mentioned, it does this by a process called heat exchange. Basically, the A/C works by literally getting the heat from inside of your room  and dumping it outside. Same principle w/ the heater A/C, it takes the heat from outside and dumps it inside the room. It does this with the help of a chemical called a refrigerant like Freon. Refrigerants have the ability to change it's state from liquid to gas (it evaporates) or gas to liquid (it condenses) by simply changing the pressure of its container. Refrigerants are liquid when kept at high pressure and gas at lower pressures. That is why the parts mentioned earlier is called the evaporator and condenser. Heat exchange happens during the transition of this chemical between gas and liquid state.  From here on, just remember the principle that when a liquid evaporates, it takes the heat with it and when it condenses, it releases the heat. That is why you feel cool as the wind blows  while you're sweating - your sweat evaporates taking the heat off your skin. Same principle during water distillation process where the hot steam is changed back to water after cooling it - releasing the heat of the steam.

What the A/C simply does is change the state of the refrigerant from liquid to gas and vice versa in a cycle. Changes in  the pressure is being taken care of by the compressor - the part where you need electricity (along with the fan blowers). Since the evaporator is inside your room and the condenser is outside, as the refrigerant evaporates inside the room, it takes the heat from inside the room and when it condenses back outside the room, it releases the heat outside. The result, nice cool (or warm) room. The blowers, or fans just helps circulate the air around the condenser and evaporator for a more efficient heat exchange.

So it is important to clean the A/C particularly the evaporators and condensers to maintain an efficient heat exchange and ensure proper cooling. In my case, the evaporator is freezing up since it is filled with dirt blocking the flow of air and preventing proper heat transfer from inside the room, to the point it is cool enough to form ice. The ice formation blocks the flow of air further worsening the problem. I guess the condenser is much worse (since it is outside) the room. If the condenser cannot properly release the heat, it adds to the problem. This, aside from the fact that you are wasting electricity in the process.

Enough of the scientific stuff, let's start cleaning :)

The last cleaning was about a year ago, look at how dirty it is...

Here is the view of the evaporator with the front panel removed. The black wire sticking out is the temperature sensor.

This is the dirt accumulated on the evaporator. This prevents the proper flow of air coming from the fan blower.

Sludge and dirt spilled all over the place as soon as I'm able to pull it out from the wall

On the inside, more sludge, dirt and rust. 

Before getting the system wet, electrical connections must first be secured. Most A/C designs enable you to pull out the electronics and electrical box by just simply undoing a couple of screws and connectors. This must be removed to prevent the electronics from getting wet. I'm gonna clean it by spraying water all over the place.

I just snapped a photo of the connections so I can put it all back properly once done.

The rest of the electrical connectors going to the compressors and blowers are wrapped in plastic and secured in place. The whole box of electronics is completely pulled out.











Then I cleaned the whole block by spraying water on to it to remove the dirt and sludge. I gave special attention and caution in cleaning the evaporators and condensers by brushing it lightly and spraying some detergent for easier dirt removal. Have to be careful in doing this since these have delicate aluminum fins and can be bent out of shape with a light force. These fins must be kept as straight as possible to allow proper air flow. Using a water sprayer with a compressor will be a very big help in properly cleaning these vital parts.

After cleaning, here are the results.

The compressor.

Also, I sprayed some WD-40 on the metal and corroded parts to help protect it from further corrosion. Any break on these parts, especially on the copper tubes that contain the refrigerant means a costly repir or end of life for the A/C.

Here is the evaporator (front of the unit).



This is the part that facing inside of the wall. Also shows the fan blower to blow off air for heat exchange. Be sure to clean this as well. Accumulation of dirt on these blowers can alter the shape of the fins leading to weaker air flow.

 Closer view of the blower fan facing the condenser. This A/C has a common motor for the condenser and evaporator fan. Both fans are connected on a common shaft which is a very efficient design.This is common for window type A/C's.

Other designs have separate motors for these blowers particularly split type A/C. This is so called since the condenser and evaporator parts are split up into two units. The evaporator is inside the room while the condenser is completely outside connected by tubes where the refrigerant circulates.









And so, after letting it dry up for half an hour or so, I just reconnected the electricals and screw everything back in place. The last challenge is lifting this back up on the wall for a good six feet. I did this asking for an extra pair of hands.

The A/C is now operating like new, nice cool room and no more freezing problems. Physically demanding activity but rewarding as well. Had a lot of fun as always...

Have a great weekend everyone :)

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