Leaving water temperature is not used to determine if air is present. Leaving water temperature is used to determine condenser approach. 'Higher condenser approaches' means some things and 'lower condenser approaches' mean other things. Low condenser approach means that the tubes are not particularly fouled and that you have good heat transfer. If you have good heat transfer, then you probably aren't low on charge and that your high condenser pressure is probably due to air in the chiller. If you had high condenser pressure AND a high condenser approach temperature then (perhaps) you are low on charge or your tubes are fouled. Remember that all equipment is in the process of degrading in performance. They all have some degree of fouled tubes, non-perfect charge, non-condensibles, etc. You START with the biggest problems and work down until you get a satisfactory piece of equipment.
Originally Posted by milkyway