Absolutely bang on mate. Air conditioning units are one of the worse things ever created. All fine and dandy getting a blast of cold air but its the quality of air. In order for this system to function effectively the area must be fully enclosed, whether that be your car, house, office or pigeon transporter. The warm air gets circulated through a cooler and re-enters as cold air.... but its the same air. In these huge office workplace environments with AC units there is a rise in people off work with the usual illness, cold , flu etc., all this being attributed by the AC system. The air contains bugs and viruses only for it to be constantly circulated...... this applies to transporters with AC units, youngsters with sickness will spread this through the entire transporter. Just my opinion