Chapter 6—REFRIGERATION AND AIR CONDITIONINGhumidistat setting will close the heating switch,energizing the reheaters.MAINTENANCEProper attention to maintenance checks willoften allow you to detect developing troubles intime to take corrective action. Since mostbreakdowns often occur at the most inopportunetime, periodic checks and maintenance willprove to be well worthwhile to avoidmalfunctions.The two-position control system can easily bechecked out in a reasonably short time. Thecheckout period should be at least every threemonths or more often if it proves to be necessary.Inspection and checks should be conducted at thebeginning of the cooling season and about mid-way. The same should be done for the heatingseason.Sensing elements should be inspected and anydust accumulations removed. Thermostaticsensing elements should have dust and dirt re-moved with a soft brush, and the sensing elementsin humidistats should be blown off gently withair so as not to damage the elements.Magnetic valves should be checked for opera-tion. Be sure that the valves are opening and clos-ing completely.Setpoints of the thermostats and humidistatsshould be checked with a calibrated thermometerand a reliable humidity indicator.When servicing the two-position controlsystem there are three possible areas where trou-ble may occur:1. The sensing element and its associatedmechanism.2. The magnetic valves that control the flowor refrigerant.3. The wiring system which connects the sen-sing elements to the solenoids of the magneticvalves and the controller of the electric heaters.DETECTING ANDCORRECTING TROUBLESFaulty operation of the refrigerating and airconditioning plants is indicated by various definitesymptoms. Information in figures 6-12 and 6-13indicates some possible troubles that may be en-countered, the possible causes of these troubles,and the corrective action which may be taken. Butremember always consult the manufacturer’stechnical manual before attempting any repair oradjustment on your equipment.6-17
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