<apex:inputCheckBox id="filter1" value="{!fcb}">
        <apex:actionSupport event="onclick" action="{!findNearby}" rerender="geomap"/>
        </apex:inputCheckBox>
        <apex:outputLabel for="filter1" value="nur aus verwandter Branche ({!currentAccount.WZ_Abteilung__c})" />

So there is no actual field on the account, it just "exists" on the visualforce page.

I am passing the value to my class who runs different queries depending whether this checkbox is true or false:
 

// FILTER 1 (Branche)
     public boolean fcb { get; set; }
     // FILTER 2 (Owner)
     public boolean fco { get; set; }
     // FILTER 3 (perfect fit)
     public boolean fcf { get; set; }
        
     public FindNearbyController (boolean fcb, boolean fco, boolean fcf) {
     this.fcb = fcb;
     this.fco = fco;
     this.fcf = fcf;
     }

if (fcb == true && fco == false)  {
       
       warehouses =  [
                               SELECT Id, Name,URL_zum_CC__c,Mitarbeiternzahl_final__c,Auftragseingangstyp__c,AD_MS_Rel_Anzahl_bez__c,Vollst_ndiger_Name__c,ShippingStreet,LocateCity__longitude__s, LocateCity__latitude__s, OwnerId,GeoLocPosition__c,Accountinhaber_Text__c,WirtschaftszweigWZ08__c,WZ_Code_ebene_2__c,AE_letzte_12_Monate__c,anzeigendaten_de_ID_account__c,indexurl__c
                               FROM Account 
                               WHERE Letzte_gew_Opp_OneSales_in_Tagen__c <= :decimal.valueof(myTime) AND DISTANCE(LocateCity__c, GEOLOCATION(:dlat,:dlon), 'km') < :decimal.valueof(myInput) AND Id != :theaccId AND WZ_Code_ebene_2__c= :currentAccount.WZ_Code_ebene_2__c
                               ORDER BY DISTANCE(LocateCity__c, GEOLOCATION(:dlat,:dlon), 'km')  
                               LIMIT :recordLimit
                      ];

What I am trying to achieve is to set {!fcb} by default to true, so that the 1st query runs with pageload. I already tried "selected = 'true'". While the checkbox gets actually checked, the query does not get fired. Only when I "re-trigger" my "action" it will query. 

I would conclude that 'selecetd = true' is only for "visual" and there is no actual value getting passed to the controller?! Or is event="onclick" the problem?

How can I make this work? That the query runs on pageload with {!fcb} set to true.

Thanks in Advance!