100% Fresh Air Package Unit A/C

If you are using it for fresh air only and no cooling, then you will still have to change the filters and maintain the fan motor and blower assembly....it won't hurt the compressor...

am asking if i use it for cooling but with 100% fresh air , that's mean i will not use the return air. is the compressor designed to cool return air and some of fresh air or the compressor can cool the 100%fresh air.

Are you asking if it can draw outside air and circulate it into the home. Yes it can. There is more to it if as an AC unit you want it to be efficient. Damper need to be added and controlled to switch between drawing from the inside or the outside.

This system may also provide heating you don't want to draw 30 degree air in and heat it. Or draw 90 degree air in and cool it. So the duct work need some type of damper to switch it. The damper needs to be controlled by system. You don't want to have to remember to have to do it manually.

What is the outdoor ambient air temperature and humidity? What indoor temperature and humidity are you trying to maintain? What are the loads you must accommodate (heat conduction and air infiltration into the room, people and energy-producing equipment in the room)? What is the capacity of the AC unit under various conditions?

If you alrady have the return air duct inplace and you are adding 100% outside air duct, add two damper packages and an economizer controller. In that case, you will be able to calculate a "minimum" outside air volume during cold winter and hot summer months, but have the ability for "free cooling" when the outside air is between 45 - 60 degrees F. 100% Outside air units are designed for adding ventilation air to a space or process (kitchen, laboratory, etc.) and only condition the air to a minimum temperature. A secondary unit will then condition the space for comfort. See below: https://www.trane.com/commercial/uploads/pdf/673/admapn020en_0406.pdf http://www.makeupairresidential.com/?gclid=CJKy-c3A_cUCFVKPHwod6rgAbg

Another issue you have not addressed is how tight the building is. If the building is too tight, your static pressure will be way off creating more strain on the air handler fan motor. Also if the temperature difference between the inside air and outside air is too great, your condenser unit will be operating with too much head pressure and it will damage the compressor and shorten its life.

The capacity of the unit must have been selected based on heat load or cooling load calculations with certain number of air changes per hour and other parameters. If you change it now it will affect the capacity and performance of the equipment.

I used to work maintenance in a hospital. The surgery dept. was all one pass air to prevent cross contamination. Each surgery room had a ceiling exhaust fan to deal with the positive air pressure created by the supply air. Air conditioners do not have air cooled compressors. The compressor needs to be hot. Otherwise there will be a chance of liquid refrigerant returning to the compressor, and it would damage the compressor. What cooling there is, is supplied by the remaining cooled evaporated refrigerant in the returning suction line.

Yes you can.

The compressor will run continuously unless the outside temp gets below the set temp of the room being cooled.

The room will be positively pressurised and will require an exhaust opening.

If it is hot outside the room will get cooler but maybe not cool enough.

Water will piss from the condensate drain all the time

The evaporator may ice up.

If the return air filter is on the duct then you will be pulling unfiltered air through your evaporator and into the room.

If that is good for you then do it.