Tag Archives: air conditioning

Dirty Condenser Coils

The condenser coil shown here, was completely covered with seedlings from cotton wood trees. Every spring, these seedlings can quickly cover a condenser coil. If you cleaned the coil early enough, using a brush, it will just peel off the face of the coil.

Cotton Woods Trouble
Cotton Wood Troubles

The next image shows a small window AC with the outer cover removed. The back side of the condenser coil is very dirty. Dirt that has been baked on will need to be cleaned using coil cleaner and a pressure washer. A pressure washer must be used carefully, as it can very quickly bend over the aluminum fins on the condenser coil.

Dirty Condenser
Dirty Condenser

Keep the spray parallel to the fins and do not get too close. Hitting the coil with high pressure water at an angle will quickly flatten the fins. Where possible, try not to push the dirt further into the coil. Use a soft bristled brush to clean off the surface of the coil, then, spray the water in the opposite direction of the air flow, to push the dirt out.

In most cases, this is not easy to do. However, spraying in a counter flow direction will prevent the large dirt particles from becoming lodged deep in the coil.

“I have seen many units that look clean on the surface, but when you look closely between the fins, there is dirt packed in tight.  The dirt is very difficult to remove and also causes the unit to shut down on hot day.“

After spraying in a counter flow direction, switch to the opposite side and then try to work the rest of the dirt down and through coil.

Coil cleaners can be used to loosen dirt but be sure to completely rinse the cleaners off. Residual cleaning fluids left behind, can deteriorate the aluminum fins. If the coil is relatively clean, then just use water, it works well and is environmentally safe.

An air conditioning system works by absorbing heat from inside the building and rejecting that heat to the outside. If the heat cannot be rejected efficiently, the cooling process will slow down or even stop. Larger air conditioning systems, have a pressure safety device, that will shut down the compressor, if the pressure is high. Then, it may need to be manually reset, by cycling the power or pushing the reset button. Smaller systems, will use an internal pressure relief which is built into the compressor. The compressor operation will become very loud if this occurs or the compressor will shut off, on an internal thermal overload which should reset after several hours.

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Keep the AC going on hot summer days.

Want to know if you air conditioning is working properly? Wait until it gets hot and then you will find out. If the AC can keep up to the load, then it is likely working properly.  If it cannot keep up or quits then you got issues. The hottest days of the year, is a bad time to call the for the AC guy, there could be 100’s calls ahead of you.

Air Conditioning systems, are sized to work on what is expected to be the hottest days of the year, which is about 97.5% of the time, for your area. This is the design temperature, that the engineer used to determined the size of the air conditioner. At this temperature, the amount of heat that is gained in a building, will be equal to the amount of  heat being absorbed by AC.  If more heat is gained, than can be absorbed, then the room temperature is going up.  The designer will allow for a little more capacity, and use a 10% safety margin and will select up,  the next available equipment size, above the design requirements.

If the compressor is running continuously without cycling off,  your AC is running at maximum capacity. This is normal on very hot and humid days. If the AC cannot keep up or if it is not the hottest days of the year, and your AC is running continuously just to keep up, then there is a problem.

There can be a lot of hidden issues with an AC system that will reduce efficiency but do not get noticed until weather gets hot. This loss of efficiency, affects your AC all year and it can cost you twice as much for electricity.  It can also damage the compressor and controls and will most likely to fail, when it is in highest demand, on the hottest days of the year.

Image of a AC system used in residential housing
Typical split AC system

AC Tip.

Two piece air conditioners have an indoor coil and outdoor coil and compressor. The two are connected with two copper pipes, a big pipe and a little pipe. The big pipe should be cool (~60°F to ~50°F) and the little pipe should be warm. (~80°F to ~90°F) If the big pipe is cold, ice forming on the pipe or the pipe is too warm then there could be a problem with the refrigerant charge.

If the little pipe is hot, then the condenser could be dirty or over charged with refrigerant. If it is too cool, where the line connects to the indoor coil, there could be a clogged filter, pinched line or  it could be under charged.

These problems can only be repaired by a qualified Refrigeration/AC Technician. Do not attempt to repair these systems yourself.