iFAQ comes with a Search Module which allows you to search articles.
1. Select Menus → [A menu type, can be a hidden menu type] from the drop-down menu on the back-end of your Joomla! installation, then create a iFAQ → Search Menu item and save; Under the Category tab you can choose which categories you want to exclude from search;
2. Select Extensions → Module Manager, either create a iFAQ Search Module OR edit and enable an existing one. Then configure the module according to your needs.