Use of Air Cooler in conditioned space

This will depend on how much heat input there is into the zone in question. If there only a few people and not much machinery, electronics, or other heat sources, the temperature will not rise very fast. If so, you may be able just to ride through a short outage like this.

If the zone in question is open to adjacent zones, the cooling in the other zones will assist with this zone, and maybe you need to do nothing.

A dry air fan will not cool the air, but it will feel cooler to the people in the area.

An evaporative air cooler will increase the RH of the area, and you should calculate how much water will evaporate and how high the RH will rise, especially if electrical equipment could be adversely affected.

There are also portable refrigerated air conditioners, with duct hoses to supply the condenser with outdoor air and also exhaust outdoors.

If the other units can handle the load, use a portable fan, or fans, to circulate the air through the zones. Place them at the edge of the dead zone, blowing outward.

You could attach ductwork from 1 or more of the surrounding zones to the dead zone and install dampers in between the zones. Then you would be able to open the dampers to cool the area while you are setting the failed circuit, and close them once its up and running.

First post, hope it helps.

Thank You. Yes, all suggestions would definitely help as we try to solve a given problem. I have 10 different circuits. I am looking at a possible failure in any of the circuit. During that failure, how to provide comfort is my question. Yes, your suggestion can be a possibel option.