Hi

We are facing similar problem like guptamik's.

As new home owners, I am at a loss to locate the "Coils in the outdoor unit" as suggested by Iceberg.

Outside our house, I found a box in which I can see a fan working.

What am I missing.......

Please reply

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Best regards

Lali

In Industrial systems the Hot Air and Cold Air is made to use a single duct system. BUT the systems are independent and seperate from each other and a DAMPER or a BAFFLE isolates the air flow. This way the isolation of the machinery takes place.
In the domestic systems the systems are isolated, BUT the evaporating coil is placed on top of the furnace. You can see the 'A' frame structure in the picture over the furnace section and beneath the plenum. This is the exact location in most of the in home systems. Plenum is the big air box over the furnace into which the fan pumps the Hot and Cold Air, from within the house through a RE-Circulation Duct. {The A frame is the evaporating coil of the A/C system}
During the severe winters when the demand on the heating is excessive and hot air passing into the plenum unduly heats the 'FREON" gas inside this A frame, here is a tendency to loose part of the gas due to excessive pressure
generated by the HEAT*with in the system and into the A/C system. But we never notice this till one fine day when we really need the Cooling system. For normal usage it will suffice. But on successive hot and hotter days the demand on the system cannot be met and will certainly call for re charging and it might cost a hundred bucks to get this job completed. It is good to get these done or prepare yourself during the start when the temperatures are about 21 to 24 degrees Celsius, which is the normal room temperature one expects to maintain. Some keep it higher to save energy and costs. For them 26-27 is the norm. Since the AC takes away the humidity, we do not feel the few extra degrees by which the room is jacked up.
In the NEWER systems they fit fans with multiple speeds, which is designed and then incorporated to push a larger quantity and also with higher velocity to provide you with ample HOT and COLD air and you never experience the the deficiency as it maintains a steady temerature throughout the house unless the registers or a damper is used to control the same. This feature could be incorporated even into some of the older generation units. A few are passed beyond their prime to do anything other than the total upgrading.
Now coming to the cleaning of the ducts, the cooling coils air filters etc., though might enhance the performance slightly, say by a point or two, has very little improvement other than in the environment or the ambiance. But on a hot sunny day you can see the dust flying off the carpets which is the culprit in this and it sure is a collector of all the sins and the only way you can keep a place and all of the equipment clean is by the physical removal of the same.
I surely would urge a systematic vaccuming of the same or removal of the dusts with a moist cloth or with a static removing material.(coated towelette).
So, be guided by this.
I would like you to read all of the four numerical pages which will provide you with the total system as fitted in most of our homes. Things have advanced further in this HVAC field since then and the material linked herewith is from a generation behind. But will give ample knowledge to develop and explore the physical machinery as fitted to your place.

Here is something to read and understand for the Long Week End.

Hope this helps.

Freddie.

http://www.popularmechanics.com/home_journal/home_improvement/1275001.html?page=3

*This build up of heat is removed or alleviated or made a moot point by the newer faster fans. A hundred bucks a year adds up as this problem is reccurring, unless we have cooler summers when we fail to notice the loss.